Casper Ruud advanced to his second Grand Slam final and his first at the US Open with a four-set win against Karen Khachanov on Friday. One point might have made all the difference.

At 6/5 in the first-set tie-break, the pair engaged in a long rally. Neither man took control of the point until Ruud unleashed a backhand up the line that Khachanov missed into the net

The 55-shot rally not only earned Ruud the set, but gave him a heavy dose of momentum leading into the set set, which he claimed 6-2.

“It was a very important point in the match. Of course, set point. I had not wasted two because he served well on the two previous set points. I knew this [was] a chance to win the first set. I'm on my serve,” Ruud recalled.

“I missed a serve by small margins the first serve. Looked like it could be an ace. Second serve we played for the rally. I think we both just refused to do a mistake knowing how important that point is.”

“Like I said, I think it was a key factor to win the second set, and that gave of course motivation and energy to play good and keep going in the second.”

The 55-stroke rally was the longest of the tournament as of the end of the match, according to tournament officials