World No. 1 Roger Federer booked his spot in the semifinal of the Indian Wells Masters final by edging past Borna Coric 5-7, 6-4, 6-4.
The Swiss superstar survived a stern test from world number 49 Coric but managed to hold on for a 17-0 record this year, surpassing his prior career-best calendar year start in 2006 when he opened with 16 wins.
"It took a while to get the record," Federer said. "But I'm happy. It was just a fighting match .... It didn't come easy, so I had to go get it. "I got a little bit lucky. I hung tough and put a lot of effort into it to get the record.
"The focus has to be the finals right now. But it's nice to get off to a good start this year, and I hope I can play well again tomorrow." The defending champion will be aiming for a record sixth Indian Wells title when he squares off against world number eight Juan Martin Del Potro in Sunday's championship match.
The 36-year-old Federer said he had to draw on every ounce of experience and mental toughness to pull out the match. "Margins are slim at the top of the game," he said. "And I have been there so many times.
"You just hope to take the right decisions along the way, and then it ends up falling your way. "But for that you need to have a very positive mindset. You need to be match-tough, you need to be confident, have experience, and I think I have a bit of all of that right now."
Down a set and trailing 4-2 in the second, Federer had to claw his way back from the brink of defeat. In the third set he fell behind again 4-3 but won the final 11 points of the match to claim the victory.
Federer clinched the match when Coric hit a shot wide. The ball was called out but Coric challenged and after the video review the original call was confirmed.
"Borna was incredibly steady," Federer said. "Those 10 minutes when I was down a set and a break it was hard for me to accept. "I got a bit lucky. It was a good match."
Federer had not dropped a set (8-0) entering the semi-final. But he looked out of sorts in the opening set Saturday as Croatia's Coric took it handily. The match was played under difficult conditions with winds swirling around the main stadium. Federer said he had to be conservative with his shotmaking to get back in it. "At some point you are happy with very little," Federer said.
Former US Open winner Del Potro improved to 16-3 on the season as he stormed past the hard-serving Canadian Milos Raonic 6-2, 6-3 in just 65 minutes.
Del Potro is looking for his 22nd career and second straight ATP title in a row after winning earlier this month in Acapulco where he beat three top eight players in a row. "I broke his serve quick in both sets and that gave me control of the match," said Del Potro.
"It was an easier match than I expected." Federer is 18-6 lifetime against Del Potro, having rallied to win the last two contests in three sets, including a 6-7 (5/7), 6-4, 6-3 victory in the championship game last year in Federer's hometown of Basel.
Federer said he is expecting another grueling war of attrition with the Argentinian. "We have had a lot of close matches. Big matches, close matches," he said. "Jeez, I just tried to think back at the French Open semis, US Open finals, Olympic semis, Basel finals. Just three-setters, five-setters the whole way," said Federer. Del Potro said he will be the underdog against Federer.
"He's the favorite to win tomorrow," Del Potro said. "But I beat him in the past, and I know I can repeat that. But it is not easy."