Ashton and Strettle ran in two tries each as last season’s Heineken Cup runners-up opened Pool One with a precious win against the French club they famously demolished 46-6 at Twickenham in April.

If Strettle is overlooked by England when they name their squad for the autumn’s QBE Series on Wednesday, then he could have done little more than produce his two brilliant finishes.

Andy Farrell, England’s backs coach, watched from the stands as Strettle showed his predatory instincts when there was no margin for error.

While he enhanced his slim prospects of selection by Stuart Lancaster, Ashton justified the misgivings over his inclusion with a typically erratic afternoon.

His tries were trademark Ashton, but so too were the moments of poor judgement that can prove so costly to his team.

A third wing in Clermont’s former All Black Zac Guildford also plundered a brace, although it was his error that enabled Ashton to grab the try that decided a tight contest.

The Top 14 leaders will take comfort from the bonus point salvaged at Allianz Park that could prove crucial in deciding a pool shared by Sale and Munster.

Man-of-the-match Charlie Hodgson was superb for Saracens, finishing with 10 points and pulling the strings superbly until his 76th replacement by Owen Farrell, who returned after three weeks out with a thigh strain.

The early danger came from farther down the backline, however, with Strettle and Ashton combining to exploit a fourth-minute overlap.

Strettle escaped down the left touchline before feeding the scoring pass to Ashton, via an intended intercept from Wesley Fofana.

It was then the turn of Clermont’s wings to spring into action in a swift response that nudged the Top 14 pacesetters into the lead.

Noa Nakaitaci bulldozed through midfield, the ball was recycled and Guildford was able to touch down in the corner despite Brad Barritt’s attempt at placing himself beneath the ball.

Fly-half Camille Lopez converted and added a penalty and Clermont were within fingertips of adding a second try but Fofana spilt his fly-half’s unkind pass forward with the whitewash at his mercy.

Saracens had spent much of the first quarter defending, but they only needed a sniff of the whitewash to plunder the next score in the 28th minute.

A quick tap penalty from scrum-half Richard Wigglesworth opened up holes, but it took a brilliant finish from Strettle to foil a superb covering tackle from Nick Abendanon.

Will Fraser, a rival for Chris Robshaw’s England openside jersey, produced a crucial turnover inches short of his whitewash just as Clermont players were lining up to drive over.

Saracens led 24-6 at half-time of April’s semi-final but the 10-10 scoreline at Allianz Park told the story of a far tighter contest that was being shaded by the French visitors.

Lopez replied to a Hodgson penalty with a drop goal, before Guildford struck again by snatching Ludovic Radoslavjevic’s box kick from under the nose of Alex Goode and evading a tackle from Billy Vunipola to cross in the corner.

For the second time Saracens’ response was issued by Strettle, who took Goode’s pass and tip-toed around a lunge from Fritz Lee before diving over.

A bizarre jumping challenge from Ashton enabled Lopez to boot a penalty, Hodgson replied in kind, and then Clermont had a try disallowed after Damien Chouly had struck Neil de Kock off the ball.

Seconds later Saracens surged ahead when Guildford misjudged a hanging kick from Hodgson, enabling Ashton to gobble up the loose ball and escape a flailing Abendanon to touch down.

Hodgson converted and Saracens did a professional job of closing out the match in the final quarter, denying Clermont a sniff of their line.