(Updates after late matches)
* Murray knocks out Mahut at Queen's
* Briton returns after four-week absence
LONDON, June 13 (Reuters) - Andy Murray emerged unscathed as he completed back-to-back wins at a blustery Aegon Championships on Thursday in his first matches following a four-week break caused by a back injury.
Gusting winds and two awkward opponents could not blow Murray off course as he first completed a rain-delayed 6-3 7-6 (4) win over Frenchman Nicolas Mahut before returning 3-1/2 hours later to crush Australian Marinko Matosevic 6-2 6-2 for a place in the quarter-finals.
Playing two matches within a short space of time at a chilly and damp Queen's Club was probably not ideal for a man who had to pull out of the French Open with a lower-back injury but Murray made sure he did not have to hang around longer than necessary - even if he had American actor Kevin Spacey looking on.
After easing past Mahut in a match that had been suspended at 2-2 in the second set on Wednesday, Murray showed his class on grass as he outplayed Matosevic at the net and from the baseline with a flow of sizzling winners.
It was so windy at Queen's Club that the ballgirls had to work overtime to keep flying debris off the court but it was the winners flying off Murray's racket that drew nods of appreciation from coach Ivan Lendl.
"(Today) the back felt great especially with the conditions we have had. It is very cold and I'm sure, as anyone who has had a back problem knows, that's not good," Murray said in a courtside interview.
"But... it feels great and that is probably the most satisfying thing. I feel pretty good physically.
"I have been moving fairly well in the first couple of matches and hopefully that will get better."
Frenchman Jo-Wilfried Tsonga was another player who had to work a double shift on Thursday as organisers tried to get the grasscourt event back on schedule following Wednesday's multiple rain delays.
He beat compatriot Edouard Roger-Vasselin 6-3 6-7(2) 6-3 but then appeared rather grumpy during a 7-5 5-7 6-3 win over Dutchman Igor Sijsling.
Fourth seed Tsonga, who reached the French Open semi-finals last week, was left battered and bruised after being stretched into six sets on Thursday.
He recovered from a heavy fall towards the end of the second set against Sijsling and booked his place in the last eight when his opponent rolled a forehand into the net on match point.
"Of course I'm tired. The body is not feeling so good. I'm a bit sick of the court today because there was a lot of wind... so it wasn't an easy day," summed up Tsonga.
Former champion Lleyton Hewitt showed he can still do damage on the slick grass as he hustled past big-serving American sixth seed Sam Querrey 5-7 6-3 6-4 in a third-round encounter.
Second-seeded Czech Tomas Berdych also found his groove to record a 6-3 6-4 third-round win over Slovenia's Grega Zemlja. (Reporting by Pritha Sarkar, editing by Tony Jimenez and Alison Wildey)