After six matches, Liem won 4-2. The duo went neck-on-neck in the first four games, grabbing two wins each, forcing a tie break of two blitz chess games. This style of chess is one of Liem's assets, having won the World Blitz Chess Championship title in 2013.
He did not meet any difficulties in winning both matches.
"I am really sorry for spoiling Jan's birthday. It was an interesting match, although I am a little disappointed because of poor performance in the second and third games," Liem said.
A month ago, the two masters drew one and Duda, with Jan, the world No 15, winning one in the Charity Cup.
It was the second remarkable victory for Liem, who is currently director of the SPICE Chess Academy and captain of the US's Webster University chess team.
Three days ago he gained attention for defeating world No 1 Magnus Carlsen, the five-time world champion, 2.5-1.5. It was Liem's first victory over the Norwegian, who has been at the top of the world for the last 12 years.
After the April 26 games, Liem has eight points, as many as Duda and Jorden van Foreest.
They are behind the two leaders Rameshbabu Praggnanandhaa of India, who has 12 points, and Carlsen, with nine.
Next, world No 32 Liem will play Grand Master Anish Giri of the Netherlands, who is No 8 in the world.
The Oslo Esports Cup is part of the Champions Chess Tour which provides up to 1.6 million USD to the highest-ranking athletes. Eight grandmasters are invited to take part in the tournament, which is taking place on April 22-28.
Liem will be Vietnam's golden hope at the coming SEA Games as he will compete in the four categories of individual and team in rapid and blitz chess./.
