Canada's Bianca Andreescu won a first-round battle of former US Open champions, defeating Britain's Emma Raducanu 6-3, 3-6, 6-2 on Wednesday to advance to the second round of the Miami Open.

There was further bad news for Britain with two-time Miami winner Andy Murray crashing out in the first round after a 6-4, 7-5 loss to Serbia's Dusan Lajovic.

Andreescu and Raducanu, both born near Toronto and both of whom won the US Open as teenagers, battled for 2.5 hours in an entertaining opening to the WTA and ATP combined tournament's main draw.

Andreescu, ranked 31st in the world, struck the ball with confidence and freedom as she dominated the first set, but Raducanu regrouped and fought back in the second.

The 2021 US Open winner went 5-3 up in the set after an epic game which she secured with her seventh break point and went on to force a third set.

But Andreescu's power proved to be too much for the tiring Raducanu, who had shown promising signs of an upturn in form by reaching the last 16 at Indian Wells.

"I thought it was a very good match from both sides. I think Emma played really well. I think the key for me was just sticking with it, fighting as much as I could," said Andreescu, who struck seven aces.

- Injury concern -

The Canadian has a tough test in the next round, where she will face seventh seed Maria Sakkari of Greece.

For the 20-year-old Raducanu, though, there was yet another injury concern with her reporting pain with her wrist.

"It's something I've been managing for some time. I just need to review after this tournament really and figure out what my next steps are," she said, adding that she may get a fresh pair of eyes to look at the problem.

World number one Iga Swiatek of Poland withdrew from the tournament on Wednesday citing a rib injury.

Murray has made a reasonably promising start to the year, reaching the final in Doha but he was well below-par as he crashed out to 76th ranked, 32-year-old Lajovic.

The Serb took his chances - winning 72 per cent of second-serve points and saved two of the three break points he faced, while converting all three opportunities on Murray's serve.

At 5-4 down in the second, Murray showed his grit to break Lajovic and raise hopes of a comeback but he was quickly broken back as he paid the price for some mis-timed strokes.

"Some days you don't hit the ball your best but my movement (also) wasn't quite there," said Murray who said he didn't see such a setback on the horizon.

"I've been practising pretty well. It's a very different court, very bouncy and much faster than last week (in Indian Wells), very different to the practice courts and...I just struggled a bit," he said.

Emilio Nava defeated John Isner in an all-American clash, the Californian triumphing 7-6 (7-5), 7-6 (7-4) playing positive, attacking tennis throughout.

The 21-year-old Nava ranked 182nd was rewarded for his attacking approach against the 37-year-old Isner, and faces another American in the second round when he comes up against the top US player in the world, tenth-ranked Taylor Fritz.

Another American Brandon Nakashima delighted the home crowd with his big-hitting approach delivering a 7-6 (7-3), 6-3 win against German Oscar Otte.

Italian Fabio Fognini crashed out to Germany's Jan-Lennard Struff, hurling his racket as he lost 6-4, 7-5, 6-4.

Italian Camila Giorgi needed three hours and 32 minutes to defeat Estonian Kaia Kanepi 7-6 (7/4), 6-7 (4/7), 7-6 (7/4), tying for the longest WTA main-draw match of the season.

Shelby Rogers beat fellow-American Sloane Stephens 6-4, 3-6, 6-2 eliminating the last US woman to win in Miami, in 2018.

Rogers has won seven straight matches against her compatriots but faces a daunting task in the second round against world number two and Australian Open champion Aryna Sabalenka.

Madison Brengle moved into the second round after Amanda Anisimova retired in the second set of their all-American encounter. Anisimova trailed 7-6 (7/5), 5-2 when she retired.

Canadian qualifier Katherine Sebov claimed her first career main-draw victory at a WTA 1000 event by beating 17-year-old Czech Linda Fruhvirtova 6-2, 4-6, 6-4.

Sebov earns a chance to take on world number three Jessica Pegula in the second round.