World No.1 Iga Swiatek emerged from a rain delay on Saturday to beat American Jessica Pegula 4-6, 6-2, 6-2 and reach the San Diego Open final.

Reigning US Open champion Swiatek sprinted to a 4-2 lead in the first set before Pegula roared back, reeling off four straight games.

She then captured the first set on Swiatek’s 11th forehand error.

Heavy rain postponed the start of the second set by more than an hour and the break appeared to boost Poland’s Swiatek, who was sharper in the second set, breaking Pegula with a forehand winner on the line to level the contest at a set apiece.

In the third set, Swiatek raced to the net to catch up with a drop shot and sent a backhand down the line for a 4-2 lead she would not relinquish, improving to 4-1 head-to-head against Pegula when the American’s shot landed in the bottom of the net on match point.

“I was leading in the first set but I lost my focus in the middle of the set...I didn’t want to make that mistake again,” Swiatek said, adding that she spent the rain delay doing crossword puzzles. With her run to the semi-finals of the WTA 500 event, Pegula will break into the world top five when rankings are released after the final.