World number one Roger Federer equalled his best start to a season when he beat South Korea's Chung Hyeon to reach the Indian Wells Masters semi-final.

The defending champion claimed his 16th victory of 2018 with a 7-5 6-1 win over the world number 26 in California.

The Swiss has matched the start he made to the 2006 season, where he went on to win 33 of his first 34 matches.

He faces Borna Coric in the last four after the Croat beat South Africa's Kevin Anderson 2-6 6-4 7-6 (7-3).

Federer, searching for a record sixth title, broke Chung's serve four times as he won in one hour 23 minutes.

He won 70% of points on his first serve and hit 12 aces to beat Chung for the second time this season.

The win ensures that Federer will remain number one after the tournament is finished, while Chung will surpass Kei Nishikori as the highest-ranked Asian player.

Federer reached the final of all four Grand Slams in 2006, winning three and only losing the French Open to Rafael Nadal in four sets.

He also won four ATP Masters titles and ended the year with a win loss record of 92-5.

Following the match, Indian Wells tournament director Tommy Haas announced his retirement from the ATP Tour.

The German, who won 15 singles titles, finished eight seasons ranked in the top 20.

"The sport gave me cherished friendships, an ability to travel the world, and opportunities to create incredible memories," the 39-year-old said.