London Irish coach Dick Best believes that his club can end a 20 year wait for a glory chance but only if they can "beat the best team in the country".

That is the Exiles' supremo's analysis of the task awaiting his side as they try and stop treble-chasing Northampton from marching relentlessly on.

For the first time since English rugby's premier knockout tournament was launched in 1973, cup finalists will be decided on the same afternoon at the same ground Reading Football Club's 24,500-capacity Madejski Stadium.

Back-to-back Tetley's Bitter Cup semi finals see holders Wasps tackling rebuilt Bristol, followed by Irish opposing a Saints outfit probably minus injured England captain Matt Dawson.

While both Bristol and Wasps have previously savoured cup glory, neither Irish nor Northampton can boast membership of an exclusive club that could produce its third new recruit in as many seasons.

Only eight clubs Gloucester, Coventry, Bedford, Gosforth, Leicester, Bristol, Bath and Harlequins lifted the cup outright between 1973 and 1997.

But Wasps last season emulated first time winners Saracens the previous year, and now either Irish or Northampton, runners-up in 1980 and 1991 respectively, could complete a healthy hat-trick.

League form heavily favours Northampton, whose recent victory at Gloucester was arguably the outstanding Premiership performance this season.

They easily sent Sale packing from Franklins Gardens a fortnight later all this, after Irish had lost 64-16 against Bath, then conceded 41 points to Leicester.

Predictably, Best has made changes, most notably dropping former New Zealand All Blacks fly-half Stephen Bachop in favour of prodigious goalkicker Jarrod Cunningham, who is switched from the wing.

And up front, returning hooker Richard Kirke and number eight Rob Gallacher should bolster the Exiles' Twickenham bid, but Best remains brutally honest about the challenge ahead.

"Having played everyone in the Premiership this season, I would definitely say that Northampton are the best side in the country," he claimed.

"You only have to look through their team to see how much quality they've got. The front-row is probably the best in the country, Pat Lam has been player of the year, or thereabouts, for the last two seasons, and all their forwards are of international calibre.

"It will be a very hard game for us, but what we have to try and do is resist their obvious height and weight advantage up-front, and play the sort of game which takes them into open areas."

For Northampton, tomorrow's tie heralds a make-or-break month with regard to their treble aspirations.

They face Heineken Cup quarter-final rivals Wasps on Sunday week, followed by Premiership games against Harlequins, Bath and Leicester, a schedule which would terrify most teams.

But Saints boss John Steele, who could see Dawson missing throughout that entire three-week period, is determined his players enjoy the challenge.

"We've got a hard month ahead of us, but no-one said it was going to be easy," stated Steele.

"It is an exciting period for the club you don't get into this kind of position every day. We've got to make the most of it and enjoy it."

Bristol could only have dreamt about a Twickenham cup final appearance when they went into receivership less than two years ago, a fact not lost on rugby director Bob Dwyer.

"This weekend is all a far cry from some 20 months ago when we hardly had enough chairs for our desks, let alone players to sit on them," he said.

"We have come a long way in a short time, and we will relish what is going to be a wonderful rugby day, although it's going to be very hard to beat Wasps."

Bristol, whose 22-man squad could include seven former Richmond players making a poignant return to the Madejski Stadium less than a year after the club's professional arm folded, have never lost a semi-final.

But Wasps are in no mood to relinquish the trophy, especially with Heineken Cup qualification confirmed for this season's Twickenham winners on May 13.

"I can see it going right down to the wire, but hopefully we can pull out a victory," said Wasps' former Bristol three-quarter Josh Lewsey.

The smart money suggests a Wasps/Northampton final, yet both Bristol and Irish are good enough to upset the applecart on a day when rugby should be the real winner.