After helping Saracens to secure a home tie in the Gallagher Premiership play-offs, Billy Vunipola believes they have a massive opportunity to progress their Heineken Champions Cup aspirations if they can overcome Ospreys at StoneX Stadium on Sunday.

Sarries will be on a mission to remain in European Rugby’s elite premier club cup competition over the next two weekends as Stade Rochelais, defending champions in France's Top 14, or Gloucester await Sunday’s winners in the quarter-finals, but that will be no easy task for the current Premiership leaders.

Mark McCall's side warmed up for their return to European action with a free-flowing, entertaining 36-24 victory over London rivals Harlequins in front of an impressive 55,109 crowd at Tottenham Hotspur Stadium last weekend.

Former Sarries player Andy Farrell, fresh from coaching Ireland to a Guinness Six Nations Grand Slam, watched son and captain Owen Farrell kick 11 points before limping off with a suspected ankle injury 10 minutes from time, as Spurs fan Alex Lozowski, Sean Maitland, Nick Tompkins, Andy Christie and Maro Itoje - who all returned from Six Nations duties – shared the five tries. 

Harlequins, who also had players returning from the Six Nations, saw Marcus Smith convert two of the four tries which came from Alex Dombrandt, Joe Marchant and Cadan Murphy (two).

Man of the match Vunipola - another Tottenham supporter - admitted he soaked in the big match atmosphere and also praised referee Luke Pearce for his superb officiating throughout the 80 minutes.

“Coming out and seeing so many people, some of them maybe their first rugby game – it was awesome,” said 30-year-old Vunipola, who has not featured for England since former Sarries player Steve Borthwick took over as head coach from another former Sarries associate Eddie Jones.

“Hopefully we’ve helped them to enjoy the game and a lot of credit has to go to Luke Pearce, he refereed the game very well. Although there were times that our boys were surrounding him, I thought he did a great job and obviously Quins (Harlequins) are Quins. There’s a lot of things for us to fix but they are a very good team as well.”

Vunipola, whose older brother Mako also appeared in Saturday’s victory, insisted he has respect for the West London outfit despite the two having a tense historical rivalry.

“It’s a rivalry, it’s like a brotherly rivalry,” he added. “Obviously there’s a lot of I guess animosity there, but also respect. We respect what they do and how they play and I’m sure there’s a little bit of respect from them.”

Ospreys will arrive in NW4 fresh from beating Dragons 37-18 at their Swansea.com Stadium base to keep alive their hopes of finishing as the top Welsh region in the United Rugby Championship.

They should have their star-studded Wales Six Nations stars to grace the StoneX pitch, including captain Alun Wyn Jones, George North, Rhys Webb, Adam Beard and Joe Hawkins, Gareth Thomas and Tomas Francis.

Saracens returned to the top flight of English rugby last season, having spent the campaign before in the second-tier RFU Championship, but were eliminated in semi-finals of the European Challenge Cup, losing 25-16 to Toulon, who were beaten 30-12 by fellow French Top 14 Club Lyon in the final at the Stade Velodrome in Marseille.

And Vunipola believes Saracens, three-time winners of Heineken Champions Cup, have a massive opportunity to progress further and potentially reach the showpiece final at Dublin's Aviva Stadium on May 20.

“Last year we didn’t give our best shot,” he admitted.

“We got pumped by Toulon away and so it’s very exciting for us. It’s important for us to fight on two fronts and show we're a team that willing to do that.”

Tickets at https://www.eticketing.co.uk/saracens/EDP/Event/Index/102 or catch the action on BT Sport 1 HD from 2.30pm.