Roger Federer came out firing in the final of the ATP Masters 1000 event at Indian Wells while Dominic Thiem needed a set to adjust to what he was seeing across the net.

Thiem went on to beat Federer 3-6 6-3 7-5 to claim the biggest title of his career, collect a cheque for $1.3 million ($A1.8m) and deny Federer a record sixth title in the Californian desert.

“It just feels unreal what happened,” Thiem said. “He’s such a legend.

“It is such a pleasure to compete with you, to learn so much from you, and to play with one of the biggest legends of all time.”

Thiem fended off break-points chances in the deciding set and made his count with a forehand winner to go up 6-5, his nerveless power hitting proving too much for Federer.

The Austrian – who will move above Federer to a career-high world No.4 when the latest rankings are released on Monday – served out the two-hour match that ended with an error from Federer, a forehand dumped into the net.

Federer was in the final for the third-straight year at Indian Wells and lost for the second year in a row. He was beaten in a third-set tiebreaker by Juan Martin del Potro in 2018.

The Swiss ace Federer won his 100th career title in Dubai recently.

Thiem had lost in his previous two ATP Masters 1000 finals – both in Madrid on clay – but the 25-year-old’s solid serve held up against Federer as it had throughout the tournament.

Federer cruised through the first set in 36 minutes, breaking Thiem twice.

“The way he was playing the first set was unreal,” Thiem said.

“I had to get used to it.”

Thiem earned the only break of the second set in the fourth game and the all-important break in the 11th game of the final set.

“He did very well when he got up to the ball, stayed calm, made the shot,” Federer said.

“Just came up against somebody who was on the day a bit better when it really mattered.

“What a great week for Dominic. Wonderful playing at the very end and throughout the week. You deserve it.”