Andy Murray overcame a slow start and moved through the gears nicely to beat Australia's Matthew Ebden in his first match since splitting from coach Ivan Lendl.
The British number one, seeded sixth at the Sony Open in Miami, looked in danger after losing the opening set but turned the game around decisively, winning 12 out of 13 games to kick-start his title defence with a 3-6 6-0 6-1 win.
Murray forced two break points in the opening game but Ebden responded to the second with an unreturnable second serve, an ace and then a superb point to win the game - and then broke the Scot's serve in the next.
He saved three more break points in a 10-minute fifth game and Murray drilled a forehand into the net as another slipped away in the seventh, leaving him serving to stay in the set.
He managed that but could not prevent Ebden serving out to win the set 6-3 in 39 minutes, having won nine of 13 points when coming to the net in an otherwise even contest.
Murray had to make a good start in the second set and he did, breaking at the first attempt.
He faced two break points in the very next game after sending a forehand long, but saved both and consolidated his break.
Another followed as the Wimbledon champion began to click into gear, benefitting from a more aggressive approach as he took balls from well inside the baseline.
A tough hold took him 5-0 up in the set and he won the set when he broke again in the next, helped by a net-cord on set point.
He was broken in the opening game of the decider but responded by winning the next four and as Ebden ran out of steam, a second serve lodged sorrowfully in the net to gift Murray two break points.
He converted the first into a 5-1 lead and served out, taking his second match point as Ebden's return sailed long.
Murray paid tribute to his former coach Lendl after the match but admitted he must now find a way to win without his assistance.
Lendl helped Murray break his grand slam duck at the 2012 US Open before adding last year's SW19 title, having also won Olympic gold at London 2012, but the pair announced an amicable split earlier this week due to conflicting schedules.
"It was very different without him, it's been a hard few days," Murray told Sky Sports 3.
"He's been a big part of my career and to not have him around is going to be tough, but I just need to get on with it now and try to get back to playing my best tennis."
Reflecting on the match itself, he added: "He (Ebden) was playing well at the net in the first set.
"I had six break points, I think, but I couldn't convert. But I played better in the second and third set.
"I got broken right at the beginning of the third set, I played a sloppy game and needed to fire myself up, but I turned it around after that and won six games in a row."