Leicester powered into their third straight Premiership final as Pat Howard said goodbye to Welford Road with an unprecedented treble still very much on.

The Tigers did enough to clinch Saturday's Guinness Premiership semi-final against Bristol, setting up a mouth-watering Twickenham showdown with Gloucester next Saturday.

Howard, who is returning to his native Australia at the end of the season, watched his side run in tries through Harry Ellis and Geordan Murphy, while Andy Goode contributed 16 points with the boot.

Bristol's only try came through Sam Cox, with Danny Gray kicking their other points.

Beaten finalists in the last two seasons, Leicester went in the game as heavy favourites, and made three changes from the side that toppled Wasps on the final day of the regular season.

Tom Varndell started at wing, Alex Moreno at tight-head prop and Leo Cullen at lock, with Alesana Tuilagi, Julian White and Ben Kay all replacements.

The last side to beat the Tigers, Bristol recalled fly-half Gray for David Hill, while also making three further changes due to injury.

Neil Brew and Nathan Budgett came in for Brian Lima and Andrew Blowers, with Alfie To'oala moving across to number eight. Sean Hohneck was a late replacement for lock Roy Winters.

And three of the newcomers made an immediate impact, To'oala and Hohneck carrying the ball well and drawing a penalty which Gray slotted over.

Leicester came storming back and only some excellent tryline tackling prevented them touching down.

Long-time league leaders Bristol were getting penned in their own 22 and when Leicester got their first rolling maul going in the 12th minute, Richard Hill's side had no answer. Ellis saw a gap, peeled off the back and ran under the posts virtually unopposed. Goode added the extras.

Bristol soon resorted to foul play to try and win the forward battle and Goode made them pay with the Tigers' first penalty.

Gray quickly responded in kind but Bristol's lack of territory cost them again when Goode's penalty re-established his side's seven-point lead.

Bristol's rare forays into the Leicester half were proving effective though and a good advantage from the referee almost saw them breach the tryline. Gray made no mistake with the penalty, however.

The visitors had a let-off when Goode struck the post with Leicester's next penalty but Darren Crompton knocked on trying to catch the ball.

Leicester spread it wide from the resulting scrum and a clutch of team-mates helped drive Murphy over the line. Goode converted.

The fly-half's 60-metre penalty attempt moments later never troubled the goal and neither did Luke Arscott's effort for Bristol from similar range on the stroke of half-time.

Tuilagi replaced Varndell at the interval but it was the unchanged Bristol who struck first, Gray's cute inside pass releasing Cox who danced through the Leicester defence on the 22 for a great score. Gray blotted his copybook by missing an easy conversion.

As in the first half, Leicester responded with force and, after having a try appeal rejected, were desperately unlucky not to touch down again when Goode's clever grubber kick hit the padding of the post.

Their consolation was another Goode penalty from the resulting scrum.

At least Bristol were enjoying more time in the Leicester half but they were unable to repeat the move that earlier released Cox as the Tigers' defence held firm.

By now, both sides had made a series of changes, one of them seeing Hill replace Gray for Bristol.

But the visitors' ill-discipline continued and Goode's latest penalty made the gap 12 points with less than a quarter of the game remaining.

It took a massive tryline hit from Tuilagi to prevent David Lemi scoring Bristol's second try and putting them within a converted score of levelling.

But the game was up when flanker Joe El Abd was sin-binned late on for persistent infringement as Leicester saw out what time remained to reach their third final this season.

With Gloucester thrashing Saracens earlier in the day, it means the sides who finished first and second in the regular season - and level on points - will do battle for the title.