Leicester Tigers' captain Martin Johnson is well aware of the quality of the possible opposition for his side when the Heineken Cup semi-final draw is made next week.

The Six Nations title will long since have been determined by the time Johnson leads his team into Europe again on April 27 as the Tigers continue their quest to become the first side to retain the trophy.

But the England captain has already seen enough to expect a hard time in the semi-finals, even though Leicester saw off one of their strongest challengers in clinical fashion at Welford Road.

The 29-18 victory over the Celtic League champions was more remarkable given Leinster strode into a 10-point lead inside the first quarter.

But the Tigers hit back with a four-try burst inside 15 minutes, and Neil Back's second score just after the break ensured there was no way back for the highly-fancied Irishmen.

Leicester will discover their next opponents in just over a week's time, with Munster probably heading the list of teams to avoid.

"Their victory over Stade Francais on Saturday was probably one of the best performances in European history," said Johnson.

"Llanelli have already beaten us once this season, and won an away quarter-final, which is a rarity in itself. I don't suppose anyone will fancy playing them either. Castres will be tough opposition as well, so it's not a case of choosing who you want to face because there are four great sides left and any one of us could win it."

A controversial first-half Denis Hickie score appeared to put Leinster on the road to a shock win, only for the home side to hit back through Back, Leon Lloyd, Austin Healey and Geordan Murphy.

Healey in particular was outstanding on his return from a three-week ban, and although scrum-half Ben Willis replied for the visitors, Leinster could not breach the Tigers line again, even after Lewis Moody had been sin-binned eight minutes from time.

"It was an important win for us," admitted Johnson, whose team had lost their previous two games.

"Leinster are a very good side and we knew if we missed any tackles someone would be through.

"We didn't make the best start but we played pretty well at the back end of the first half and the beginning of the second.

"We held onto the ball, dominated territory and generally played mistake-free football."

There was more bad news for Ireland on the Six Nations front, with centre Shane Horgan being forced off after taking a bang to the ribs which threatens his participation in Sunday's opener with Wales in Dublin.

However, for England coach Clive Woodward, the outlook is brighter. Dorian West missed out yesterday after failing to overcome a groin injury, but director of rugby Dean Richards said he thought the veteran hooker would be available for Saturday's Calcutta Cup clash in Edinburgh.