British number one Andy Murray has conceded he was being troubled by a lingering left shoulder problem after he opened his Hopman Cup account with a straight-sets win over Frenchman Benoit Paire at the Perth Arena.

The world number six had few problems with Paire, himself on the comeback trail after injury, and won their clash 6-2 7-5 as Great Britain beat defending champions France 2-1 at the mixed teams tournament.

Although the French levelled the tie when Alize Cornet thrashed Heather Watson, 6-2 6-2 the Brits claimed the deciding mixed doubles in a match tiebreak, 6-4 2-6 10-8.

Murray suffered from soreness in the shoulder during and after his emphatic victory over Rafael Nadal in the season-opening tournament in Dubai last week, which he won when Novak Djokovic forfeited the final.

The dual Grand Slam champion subsequently had a scan which cleared him of any serious problems, however the shoulder again caused him discomfort in the win over Paire.

Just two weeks out from the year’s first Grand Slam, the Australian Open in Melbourne, where he has been a finalist three times, the 27-year-old conceded the pain was causing him concern.

“It is still quite sore,” he said.

“Maybe it was playing a match (in Abu Dhabi) after having a break or I just got it in the wrong position and tweaked something a little bit, but I should be fine.”

Murray said he would continue to have treatment on the shoulder.

Earlier on Monday, world number one Serena Williams needed a shot of coffee to regain her best form during her opening match at the tournament.

Perked up by a cup of coffee at the end of the first set, Williams recovered from a disastrous start to defeat Flavia Penetta 0-6 6-3 6-0 as the United States beat Italy 3-0 in their Group A tie.

After Williams gave the Americans the lead, the towering John Isner then secured the tie with a grinding three-set win over Fabio Fognini.

Isner dropped the first set, but fought back to win 5-7 7-5 7-6 (7/4) in two hours and 27 minutes.

The Americans then survived two match points to claim the dead mixed doubles rubber in a match tie-break, 6-2 2-6 11-9.