World No. 1 Roger Federer extended his winning streak Saturday in a tight semifinals victory over Borna Coric at the Indian Wells Masters in Southern California, 5-7 6-4 6-4. Federer will defend his title Sunday when he faces the winner of Milos Raonic vs. Juan Martin del Potro.

Federer looked in danger of falling to the Croat in the two-hour and 20-minute match. The Swiss legend trailed 5-7 2-4, but fought back in front of a partisan crowd, winning the final four games of the second set with two breaks.

Federer trailed 4-3 in the third set but broke Coric and won the final three games.

After the match, Federer conceded that it "was very difficult" to hold off Coric.

The 36-year-old has not lost a match in 2018, boating a 17-0 record. However, he has looked vulnerable to an upset at Indian Wells, a tournament he has won five times. Aside from Coric, Federer was tested by Federico Delbonis in the Round of 64.

By reaching the semifinals, Federer will remain No. 1. He entered the tournament with a 600-point lead over No. 2 Rafael Nadal, who has been inactive since January.

GettyImages-933079378 Federer needed three sets to defeat Borna Coric. Photo: Getty