Saracens have grown in stature since Clermont Auvergne cut them down to size

New-look Sarries ready for rematch with crack French side in Heineken Cup semi-final

If the crack French team Clermont Auvergne are taken aback by the size, strength and overt physicality of the Saracens side they face at Twickenham in this weekend's Heineken Cup semi-final, they will have only themselves to blame. Two years ago at the last-eight stage, they made the Londoners look like seven-stone weaklings and spent the afternoon kicking sand in their faces. If life was a beach for Sitiveni Sivivatu and company on that occasion, it will be more of a mountain range this time around.

"It was men against boys that day," conceded the Saracens rugby director, Mark McCall, recalling that 22-3 defeat in Watford. "We hold up our hands to that. We felt we were playing with one hand tied behind our backs – that we were fighting against people more powerful and more explosive than us.

"It marked the point when we decided to go about things differently in the strength and conditioning department. We changed the people who were working in that area and changed our player recruitment policy too.

"When we first started challenging at Heineken Cup level, we set out to be the fittest team around. But if you look at someone like Will Fraser [the flanker who would probably have been capped by England last summer but for injury problems], he was 99kg [15st 8lb]. He was as brave and tough as they come, but he was up against people 10kg heavier. So we changed things. He's 108kg now and a better player."

McCall described the acquisition of the former Ireland performance director Philip Morrow as "the best signing we've made at the club", purely because of his impact on the club's tale of the tape. But if Saracens are better able to cope with the physical threat posed by the leading clubs across the water – these things can be measured, and the numbers stack up – they must also demonstrate an ability to pass the kind of mental examination set by the very best French teams.

"There will be moments in the game," McCall acknowledged, "when we think Clermont are bloody good and it's then that we'll need to be resilient, to hang in there and show some perseverance in the knowledge that it's not going to last for ever. We can't let it affect us. If we can start well, if we can have a really solid 25 or 30 minutes and put some doubt in their minds, it will make a difference. When they get a lead they're very good at keeping you at arm's length. We have to make sure that doesn't happen."

Clermont, last year's beaten finalists, may not head for London in the best of humours: they were beaten by Racing Metro in Paris last weekend and, to make matters worse, they picked up some worrying injuries. Their captain, the international centre Aurélien Rougerie, is a major doubt for Twickenham as he struggles with an inflamed hamstring, while two high-performing loose forwards, Damien Chouly and Fritz Lee, have shoulder and knee issues respectively.

Talking of orthopaedic misery, there was a grim bulletin from Exeter. The 29-year-old lock James Hanks announced his retirement with immediate effect after failing to recover from a neck injury suffered during the Anglo-Welsh Cup semi-final victory at Bath last month. He is the third high-profile member of the Devonians' pack to quit on medical advice this season, following hard on the heels of his fellow second-rower Tom Hayes and the hooker Chris Whitehead.

"This has brought my career to an end earlier than I had envisaged, but I don't think I could have asked for any more from my time here," Hanks said, philosophically.