There was lots of action in the first round of Wijk aan Zee (shorthand for the Wijk aan Zee A-group, or to be even more long-winded, the A-Group of the Tata Steel Chess Tournament) with three decisive games out of seven and at least one other game that could easily have seen a winner.
World #1 Magnus Carlsen was not among the winners, but a relatively easy draw with Black against Anish Giri wasn't a bad result. Carlsen played the Modern, and the crisis came as early as move 9. Giri's 9.c5 forced Carlsen to think for around half an hour, but he found a good reply and just three moves or so later Giri decided it was time to bring the ship into a safe haven.
World #2 Fabiano Caruana also had the black pieces, but he managed to defeat Ding Liren when the latter's overextended center blew up.
Maxime Vachier-Lagrave also entered the winner's circle with a nice positional victory over Hou Yifan, which was made possible by some nice tactical tricks along the way.
The fourth winner was Vassily Ivanchuk, whose win was essentially a gift from Baadur Jobava. Ivanchuk's 20.c5 brought him from slightly better to slightly worse, and while that's usually a bad thing it can sometimes provoke one's opponent into getting a little too ambitious. Jobava's 25th move was an error, even if it took some neat tactics by Ivanchuk to prove it, but Jobava kept on pressing anyway in what was a dead drawn position if he had wanted it to be. He didn't, however, and started to drift--not into trouble, maybe, but certainly into danger. His 42nd move was a bit of a shocker, though, as he miscalculated something and traded into a lost pawn ending, which he resigned on the next move. Had he avoided that exchange the game would have remained draw with correct play.
Teimour Radjabov and Loek van Wely drew in a Pirc, where White was pressing at a few moments but didn't manage to make anything of it.
Ivan Saric drew with White against Levon Aronian on the white side of a Giuoco Piano with 4.0-0, and what was nothing turned into a slight edge and then something serious. It was crucial that he make the right decision on move 24; fortunately for Aronian, Saric missed his chance. 24.c6 would have had Black in all kinds of trouble.
Wesley So also had his opponent, Radoslaw Wojtaszek, in all kinds of trouble, and then he jumped into the fire a couple of times himself. Theirs was a very complex ending, and although So had the better chances most of the way it was the kind of mess where anything could happen. Both players enjoyed winning advantages at different points in the game, so perhaps a draw was the most appropriate result.
In the B-Group, six of the seven games were drawn, with the one exception being Robin van Kampen's victory over Sam Sevian in an instructive bishop vs. knight ending.
The tournament website is here, the games (with my comments) are here, and tomorrow's (A-group) pairings look like this: