Jeddah (Saudi Arabia), Dec 22 (IANS): American Learner Tien came up with a fine performance to get the better of compatriot and friend Alex Michelsen in a thrilling five-setter as his hard-fought win making him the third American to reach the summit clash of the Next Gen ATP Finals here on Saturday. Tien, who went 2-1 in Blue Group play, will face the winner of the second semifinal between Brazilian Joao Fonseca and Frenchman Luca Van Assche in the final on Sunday.

It was his win over Michelsen that made it all possible for Tien.

Over the last 10 years, Michelsen and Tien have developed a strong friendship. They train together in California and compete in Fortnite battles and table tennis duels. However, their off-court relationship was put on the sidelines in Saudi Arabia, where they produced an entertaining battle on Saturday. Their semifinal clash was played in front of a lively crowd and former World No. 1 Rafael Nadal, who was courtside at King Abdullah Sports City. The two Americans did not differ much in the opening three sets as they competed in their first ATP head-to-head meeting.

On Saturday, Michelsen powered down serves to dominate Tien physically at times. Still, the 19-year-old responded, outmanoeuvring the 20-year-old with an array of stunning angles and aggressive groundstrokes to pull Michelsen from corner to corner.

However, from the start of the fourth set, Tien dominated. The American, who won seven straight games, locked in on the baseline exchanges and rode momentum in the fifth set to advance after one hour and 36 minutes.

"I can't put it into words right now," Tien said following his win after hitting 21 winners. "I am really happy with the win but I hate it was against him, but that is just how it goes. I started smiling when I came out here and saw him on the other side of the net, but I am really happy to get through and think I played really well."