You think that the Guinness Premiership is a tight affair? Europe is no different and anyone who believes they can predict with confidence the four teams who will qualify for the semi-finals of the Heineken Cup this weekend goes into the same category as, at present, a financial services adviser.

True, Munster are strong favourites to win their 100th European match at home against the Ospreys and take the defence of the title they won last year to Dublin's Croke Park, which has been made available for the semi-final involving Harlequins or Leinster over the weekend of May 2-3. History suggests that Toulouse, Leicester and Leinster should join the holders, but certain teams this season have been proving Henry Ford's notion that history is bunk, Harlequins and Cardiff Blues among them.

“Whether we win anything or not this season, we have improved on where we were last year, which is all I ask of the players,” Dean Richards, the Harlequins director of rugby, said. “But they have huge ambition to go out and achieve something. If it doesn't happen this year, I'm pretty sure it will next year or the year after, because we have the right people in place.”

The “right people” tomorrow, for the home game against Leinster, include Nick Evans, the New Zealander whose judgment and skill at fly half were critical to winning through the pool phase. Evans has been out for four weeks with a damaged ankle but will add to the cutting edge Harlequins need if they are to reach the last four for the first time. “Leinster are a quality side and we will need a bit of luck going our way,” Richards said.

Cardiff came through the pool stages unbeaten to become top seeds for the quarter-finals, with a mixture of skill and bloody-mindedness and, for their pains, they meet Toulouse who have won the tournament three times. Only once, in 2007, have the semi-finals not featured a French club and Toulouse hit their straps in the Top 14 last weekend by disposing of Brive with something to spare.

Yet they are without Romain Millo-Chlusky and Benoît Lecouls, the forwards, while Cardiff remember the 41-17 caning they received in Toulouse at this stage a year ago. “We have matured as a squad and we are more used to playing big games on the big stage,” David Young, their director of rugby, said before this afternoon's game under a closed Millennium Stadium roof.

Eight of those who start for Leicester at the Walkers Stadium this evening have first-hand memories of the 15-12 loss to Bath in the quarter-final three years ago. It was not a proud day in Leicester's history, losing to a Bath side reduced, at one stage, to 13 men; Bath have four survivors from that day but in the two Premiership matches between the clubs this season, each has won once.