Indian Grandmaster P Harikrishna held world number one and world champion Magnus Carlsen in the fourth round of the preliminary stage of the Champions Chess Tour Airthings Masters online chess championship.

Both Harikrishna and Carlsen drew all their four games on the opening day of the tournament as matches ended late on Saturday.

The game between Harikrishna and the Norwegian ended in 24 moves after the players repeated the moves.

India number two and former world champion Viswanathan Anand had earlier drawn his games with Maxim Vachier-Lagrave, Daniil Dubov and Spaniard David Anton Guijjaro. He is in eighth place with two points.

Harikrishna will take on Dutch GM Anish Giri in the fifth round followed by games against Alexander Grischuk, Hikaru Nakamura, Ian Nepomniachtchi, Lev Aronian, Wesely So and Teimour Radjabov subsequently.

Carlsen was held to draws by Aronian, So and Radjabov also.

Nakamura, Aronian, Dubov, Radjabov and So are in the lead with 2.5 points after four round of the 12-player event.

The top eight from the preliminary rounds qualify for the quarterfinals.

The 12-player tournament runs until 3 January and has a prize fund of USD 200,000 with the winner getting richer by USD 60,000.

In the preliminary stage, the players play each other once over 11 rounds at rapid chess, before the top 8 players go forward to the knockout.

In the knockout stage, each match would be played over two days, with four rapid games each day. If the match score is 1:1 after the second day the players switch to two 5+3 blitz games followed, if needed, by Armageddon (sudden death tie-break).