Owen Farrell enjoyed a great comeback from injury but insists Saracens can still improve after their stunning 31-23 European Champions Cup triumph over Toulon.

The French side, three-time winners of the competition, had never lost a top-tier European fixture on home turf, but had no answer to a superb first-half display from Saracens.

Tries from Sean Maitland, Richard Wigglesworth and Chris Wyles helped the defending champions to a 28-9 lead early in the second half.

Toulon roared back after the break, scoring through Levan Chilachava and Bryan Habana while Maro Itoje was in the sin bin, with Leigh Halfpenny's reliable boot contributing 13 points.

But it was not enough as Farrell, who ended with 16 points to his name, kicked a late penalty to deny the hosts a losing bonus point as he played his first game since helping England whitewash Australia during the summer.

"It was a great effort from the group, to come to a place like this and get a result is a massive scalp," said Farrell.

"But there are still things to work on, our discipline was not great in the second half and I am sure we will look at that.

"Having said that, beating a terrific team like Toulon is a great start. We forced them to make individual errors, we wanted to make sure we were in the game and pushing the same way and we did that really well and hit them well around the ruck area.

"It is a great start, but that is all it is, we have got the Scarlets next week and we need to back up this result."

Farrell was also pleased to come through 80 minutes unscathed after his spell on the sidelines with a back problem.

"I was a bit stiff coming towards the end of the game but we held on," he said.

"I was ready for that, I was itching to be back out there and that was a great way to come back."

The failure to secure a losing bonus point means Toulon find themselves facing an uphill battle to get to the knock-out stage, with only the five pool winners and three best runners-up advancing to the quarter-finals.

Backs coach Mike Ford admitted losing their proud home record was a heavy blow to take, but backed his star-studded squad to bounce back against Sale next time out.

"Our defence was poor, the three tries were down to individual errors and not staying together, they did well to exploit it but there were some schoolboy errors there," said the former Bath and England coach.

"We left ourselves with a mountain to climb. I am delighted by the attitude the guys showed after the break and we were back within a score, but just a couple of key moments, a couple of key line-outs went astray when we did not execute well.

"They also took a bonus point off us. At half time we would have bitten your hand off if you had said we could get one, but with the way things turned out we are very disappointed.

"All we can do now is get back down to work, we have Sale next week which will be tough and they will be licking their lips, but we have superb players and they will respond."