Saracens director of rugby Mark McCall praised the mental resilience of his side despite suffering a convincing defeat to Racing 92 in the opening match of their Heineken Champions Cup title defence.

The reigning English and European champions, who were without the majority of their England World Cup contingent, were sunk 30-10 at the Paris La Defense Arena.

Racing ran in four tries to claim a bonus point with Alex Lozowski replying for a Saracens side who are facing a £5.4million fine and a 35-point penalty in the Gallagher Premiership for salary cap breaches.

The deadline for Saracens to officially serve notice of an appeal against that Premiership Rugby ruling is on Monday, but the PA news agency understands the club are set to accept their punishment.

Sunday's defeat in France added to Saracens' problems but McCall, while admitting the result was difficult to stomach, was happy with the way his team dug in against the 2016 and 2018 Champions Cup finalists.

"It's tough to take of course," said McCall.

"A lot of things went wrong today. We couldn't win any ball on our own lineout.

"For a lot of the second half we had nothing to hang our hats on or get our teeth into. We spent a lot of time on the back foot and defending.

"We lost some collisions in the first half for a variety of reasons but we never had the ball. But the mark of a team is when you are really up against it and the game's going against you.

"We scrapped until the end. Some of the last-ditch tackling from the likes of Sean Maitland, Duncan Taylor and Tom Whiteley was excellent.

"When Tom Whiteley got sin-binned our unwillingness to accept them scoring again with five minutes to go was magnificent.

"Those are always things that you can hang your hat on as hard as it is to take the defeat."

Racing scored four tries through Virimi Vakatawa, Teddy Thomas, Finn Russell and Wenceslas Lauret, with Maxime Machenaud kicking 10 points.

Saracens, chasing a fourth Champions Cup win in five years, could only respond through Lozowski's second-half score and scrum-half Ben Spencer's conversion and gigantic first-half penalty.

Racing fly-half Russell was delighted with his side's display but believes they can get even better.

The Scotland international, whose team led 18-3 at the break, said: "I thought it was a great performance by us.

"It was better than last week against Stade Francais. We know the Champions Cup is a sprint, so we had to start the competition well.

"They haven't got their internationals back but it doesn't matter who we are playing against. We just concentrated on ourselves to try and get the win.

"There's things to work on but on the whole it was a very good performance and we're looking forward to Munster next weekend."