Ian McGeechan expects Wasps and Leicester to "raise the bar" when English rugby's traditional heavyweights clash in Cardiff.
Their fierce rivalry continues at the Millennium Stadium, with an Anglo-Welsh Cup final place against Saracens or the Ospreys up for grabs.
Wasps boss McGeechan welcomes back England stars Danny Cipriani, Paul Sackey, Phil Vickery, Simon Shaw and James Haskell, giving the Londoners a possible edge only eight months after they beat Leicester to be crowned European champions.
But McGeechan said: “There is no doubt this is the biggest challenge we’ve faced to date this season.
“When you are in the knockout stages of any competition, you expect the opposition to raise the bar, and Leicester will be no exception.
“Of course, that requires us to do the same, but I think the history of big games between our two sides has consistently shown that Wasps and Leicester bring out the best in each other.”
McGeechan is without the services of injured back-row pair Joe Worsley (foot) and Tom Rees (knee), but a side packed with a dozen internationals still poses an immense threat.
McGeechan added: “It is good to welcome back those players who have been away on international duty.
“But is is important from a club perspective that they can successfully don their Wasps hats once again and fulfil the roles we expect them to play for the club.
“The game will also provide a fantastic experience for our younger players, with the expectation and big-game atmosphere at the Millennium Stadium being a stern challenge for them.”
England flanker Lewis Moody has lost his fitness fight to be part of Tigers’ match-day 22.
Moody, sidelined since suffering a recurrence of Achilles trouble during England’s RBS 6 Nations opener against Wales on February 2, had hoped to be involved this weekend.
But he is again absent from a Leicester side skippered by number eight Martin Corry that features current England players Tom Croft, George Chuter and Ben Kay.
In-form Italy prop Martin Castrogiovanni is also back on club duty, while scrum-half Harry Ellis makes a third successive start as he continues his comeback from a serious knee injury.
Leicester forwards coach Richard Cockerill said: “It is a massive game for the club.
“The attitude of the players has been top-class all week, and it has been pretty obvious how determined they are to do well on Saturday.
“Playing in a semi-final, on a big stage like the Millennium Stadium and against a good side like Wasps, is a great opportunity.
“Winning the trophy against the Ospreys last season was a massive achievement for the club, and we’ve said all along that we are desperate to try and repeat that success this time around.”