Fly-half Freddie Burns booted 23 points as Leicester secured a hard-fought 28-23 Aviva Premiership win over Worcester at Sixways to secure a play-off spot.
Burns leaves Welford Road for Gloucester next season but his faultless effort of six penalties, a drop-goal and a conversion saw Tigers book an away semi-final in a fortnight against Wasps.
Hooker Tom Youngs scored Leicester's only try with Worcester responding with tries from Chris Pennell, Wynand Olivier and Bryce Heem. Ryan Mills added two penalties and a conversion but two missed kicks from him and one from Ryan Lamb proved costly.
Worcester flanker Phil Dowson made his last appearance for the club as he retired to take up a coaching position at Northampton. It was his 262nd Premiership appearance to place him second on the all time list, three behind Steve Borthwick.
Dowson led the Warriors out before they dominated the opening period but despite sharp breaks from Perry Humphreys and Francois Hougaard, the home side lacked the necessary accuracy and Leicester escaped with their line intact.
With a weakened front row, Worcester struggled in the scrum and looked set for a long afternoon in that area and conceded the first points to a 12th-minute penalty from Burns. Mills soon responded with a long-range effort but a second from Burns restored the Tigers lead at the end of the first quarter.
Seven minutes later, they extended that lead with their first try of the game when Tom Youngs finished off line-out drive before the hosts produced a flowing move, which ended with Heem sending Pennell over.
Burns succeeded with a third penalty but Mills kept his side in contention with his second after the fly-half had missed a much simpler attempt moments earlier. Within two minutes of the restart, Worcester went in front for the first time when Mathew Tait was unable to collect an up-and-under and Heem collected the loose ball to run 30 metre to score.
A neat drop-goal from Burns rewarded another line-out steal from his forwards before Dowson departed to rapturous applause from the crowd.
Alafoti Faosiliva replaced him but the Leicester pack was becoming increasingly dominant with two further penalties from Burns putting them 25-18 ahead at the end of the third quarter.
Worcester brought on Lamb for his final appearance for the club before Warriors set up an exciting finish when Olivier rounded Matt Smith for a splendid solo try. Lamb missed the touchline conversion before Burns had the final say with his sixth penalty.