Soft desert sand has a way of preventing runaway trains, and chess players are not immune to the laws of physics.

In round four of the 2015 Qatar Masters, GM Li Chao drew GM Anish Giri, ending the Dutchman's 12-game drawless streak in his two Doha appearances. The two leaders thus allowed a host of others in the second traincar to reconnect with the engine.

Among those playing conductor again on 3.5/4? World Champion GM Magnus Carlsen, who will be back on board one after slipping all the way to board 23 a short time ago.

Read on to also see what commentators called the "most shocking result of the tournament" and also what this writer is calling the most stubborn attack of the tournament.

After splitting the point with a sub-2500 player in the opening round, Carlsen won his third straight today to get back atop the leaderboard. In his words, he's played "two wonderful Sicilians" to get there.

GM Magnus Carlsen took a circuitous path from board one, down to board 23, and after a few pit stops he'll be back to board one tomorrow. (Photo: Katerina Savina for Qatar Masters Open)

Down several pawns but with all the initiative in his first-ever meeting with GM Jan-Krzysztof Duda, the champ played a correct exchange sacrifice and annihilated the defenses of his teenage opponent.

Carlsen has now played a younger opponent in three of his four games, something he doesn't usually get to do "on tour" with the other world elites. Duda was nearly world junior champion earlier this year. But for some weaker tiebreaks and last-round misfortune, he would have earned that title.

Games via TWIC.

"When you look at the list of players, and trying to find people that you want to play against, there aren't that many," Carlsen said. "The ones I want to play are Anish, Vlady, people I know. The ones that it's embarrassing to...(he trailed off).

"It's not easy. There's so many underrated players and also gifted tactically. They play without fear, they play without prejudice. That's always difficult to face."

Cheer up Anish! You drew today to maintain a share of the lead, plus Carlsen said he wants to play you! (Photo: Alla Oborina for Qatar Masters Open)

Duda's loss won't stop the relentless onslaught of the Polish players in Doha. Having already sent three players to the top two boards in the opening rounds, they're sending a fourth player soon, their leader! GM Radoslaw (Radek) Wojtaszek won today with a brutal attack to get to 3.0/4.

Team Polska finished 13th at this year's European Team Championships, but they have been occupying some top boards in Doha. (Photo: Katerina Savina for Qatar Masters Open)

Analysis by GM Dejan Bojkov

Besides Carlsen, several other players on the premier boards joined Li Chao and Giri on 3.5/4. GM Wesley So won by a narrow margin in the ending, while GM Maxim Matlakov slowed the run of the early women's prize leader, GM Alexandra Kosteniuk.

GM Wesley So doesn't have the traditional "game face" before the round -- he's always good for a smile. (Photo: Katerina Savina for Qatar Master Open)

Here's So's victory over GM Vladimir Akopian, the former coach of Qatar's best player (and tournament organizer) GM Mohamed Al-Modiahki. You'd think he'd be given an easier pairing by the man who holds all the cards! The computer of course determines the matchups, and a computer is also needed to help figure out this narrow ending:

Kosteniuk's downfall came through her own creativity. The inventive 26. b5?! gave away her passed pawn but the costs were greater than the gains.

Kosteniuk loosened her grip on the bag of cash for the top female -- $8000 (there are six female prizes this year). There to catch it was GM Hou Yifan, who overtook the lead in that race by beating GM Baris Esen in yet another kingside bombardment.

Former Women's World Champion GM Alexandra Kosteniuk's invasion of the eighth rank didn't lead anywhere today. (Photo: Katerina Savina for Qatar Masters Open)

Esen could have survived had he waded his king into deeper waters. You'd think that kind of bravery would be fresh on his mind. After all, he just lost to GM Nigel Short last month when Black's monarch marched up to g4! What was required today? Walking clear across the Persian Gulf.

Former World Champion GM Vladimir Kramnik is not among the list of leaders, at least not yet. Having not played an open tournament in more than 20 years before the first iteration in Qatar, he said the opponents here give him pause.

"As a top player you look forward to playing players 27(hundred) plus," he said. "You know how to play against them."

The champ against the pesky upstart. (Photo: Katerina Savina for Qatar Masters Open)

Kramnik added that his style changes against this kind of competition, though not necessarily for the better. "I should play more normal chess but somehow I want to win too much," he explained, adding that there are too many rating points at stake.

Today he played one of those pesky 2600s, the young American GM Daniel Naroditsky, whose game went awry under the Russian's pressure on both sides of the board.

"Everyone's playing 1...d5, 2...g6 against me!" Kramnik said. "My opponent, Daniel, he never, ever played it!"

Although still trailing the leaders by a half point, Kramnik said he's comfortable with his lot in the tournament. 

"I felt a little rusty at the beginning...So far the same as last year," he said, referencing his two draw, two win start in 2014. That recovery culminated eventually in six straight wins. "I would like it to continue the same!"

Checking for improvements or car shopping? Carlsen said he recently bought a Tesla, but Bentley is the official car of the tournament.

If you were drawn in by the superlatives dropped earlier in the article, we haven't forgotten about you. Today commentator GM Peter Svidler called GM Evgeny Tomashevsky's mistake the biggest shock of the round, while his partner GM Alejandro Ramirez went further and called it the biggest shock the event. The full point reversal must have made a big impression on him since it was just 24 hours ago that GM Harika Dronavalli hung mate in one against GM Ni Hua, although that "only" cost her a half point.

Judge for yourself. Here's the tragedy from round three:

And now for today's "competitor":

For the sake of completeness, you could also be convinced to throw this howler into the mix. GM Wei Yi, whose upward career trajectory has seen little adversity, couldn't finish off a sparkling attack, then bungled his calculations in a king-and-pawn ending. The mistaken queen trade qualifies for what Kramnik warned of -- trying too hard to win against lower-rated opposition.

Despite this writer's surname, he does not speak German, so I can only assume "Bromberger" means "relentless" in North Rhine-Westphalia. In this must-see game, GM Stefan Bromberger had only two trajectories: checkmate or bust. He must have had some sriracha with his frühstück:

Like the famous Beliavsky-Nunn game from Wijk aan Zee, 1985 mentioned on the broadcast yesterday, Black only played one retreat the entire game, a backward knight move that gave check while doing so!

There may not be another grandmaster game with 3...g5 the rest of 2015, but there will be five more rounds in Qatar before the year ends. The leaders will play on the top three boards: Carlsen-Li Chao; Giri-So; and Matlakov-Kramnik. The rest of the pairings can be found here.

Carlsen enjoys walking around to see nearly every position. After his round two ended, he spent more than 30 minutes sizing up the remaining games. (Photo: Alla Oborina)

Just for fun, we close with Jakovenko-Ipatov. Why? Well it may have tied the record for most-ever pawns on a single file (five). It's possible there have been six on one file, but until one is unearthed, we will leave the "may have" here in print!

Mike Klein is on-site reporting for the official tournament and for Chess.com. This report was cross-posted in its entirety from www.qatarmastersopen.com.

2015 Qatar Masters Open | Standings After Round Four (Top 20)

The full standings can be found here.

Rk. SNo Title Name FED Rtg Pts. TB1 TB2 TB3
1 3 GM Giri, Anish NED 2784 3,5 2986 9 11
2 6 GM Li, Chao CHN 2750 3,5 2969 8 10
3 4 GM So, Wesley USA 2775 3,5 2950 7,5 9,5
4 1 GM Carlsen, Magnus NOR 2834 3,5 2874 6,5 7,5
5 21 GM Matlakov, Maxim RUS 2684 3,5 2854 7 8,5
6 79 Xu, Yinglun CHN 2470 3 2856 8 10
7 43 GM Salem, A.R. Saleh UAE 2622 3 2855 7,5 9,5
8 102 IM Vignesh, N R IND 2422 3 2853 6,5 8
9 20 GM Howell, David W L ENG 2688 3 2791 8,5 9
10 7 GM Mamedyarov, Shakhriyar AZE 2748 3 2790 7,5 9
11 5 GM Karjakin, Sergey RUS 2766 3 2790 7,5 8,5
12 14 GM Wojtaszek, Radoslaw POL 2723 3 2788 7,5 9
13 11 GM Yu, Yangyi CHN 2736 3 2784 8 9
14 2 GM Kramnik, Vladimir RUS 2796 3 2783 6 7,5
15 15 GM Korobov, Anton UKR 2713 3 2754 6,5 8
16 34 GM Swiercz, Dariusz POL 2646 3 2748 8 9
17 26 GM Dubov, Daniil RUS 2655 3 2717 8 9,5
18 18 GM Ni, Hua CHN 2693 3 2707 7 8,5
19 30 GM Ganguly, Surya Shekhar IND 2648 3 2693 7,5 9
20 22 GM Hou, Yifan CHN 2683 3 2691 6,5 8