The Irish province narrowly came out on top in last weekend’s match at Thomond Park, winning 10-3 in blustery conditions, but must now go to London and aim to pick up at least four points to keep pace with Pool 4 leaders Racing 92, who host Ospreys on Friday night.

“So, massive challenge ahead,” commented Van Graan. “We are playing against the very best team in Europe currently. They’ve got so much quality within their squad and what they do.

“I think both teams couldn’t really show everything they had on the weekend, because you only had 40 minutes to do what you wanted with ball in hand, just because of the conditions in the second half.”

The Munster boss admitted that it doesn’t get any bigger than a critical Heineken Champions Cup match against the defending champions, live on BT Sport and beIN SPORTS from 15:00 GMT.

“It was evident when the draw came out that it was going to be a brilliant two weeks in terms of the challenge,” said the South African.

“A lot of times you can’t say ‘it doesn’t get bigger than this’, but in terms of European rugby, going to London on Saturday afternoon against Saracens, they’re currently the best, so looking forward to seeing where we are.”

Munster Rugby head coach Johann van Graan has labelled his side’s Heineken Champions Cup Round 4 match at defending champions Saracens on Saturday a “massive challenge”.