The visitors notched three tries to the Warriors' one but Andy Goode outclassed Toby Flood with the boot to help Richard Hill's hosts to within sight of victory - only for late drama to silence home fans.
The early stages were cagey with both sides hitting tackles hard but struggling for fluency with ball in hand. It was left to Goode to open the scoring in the 10th minute - blasting over a penalty after Thomas Waldrom had been caught the wrong side.
Sixways erupted four minutes later when the first meaningful move of the match yielded a try for the hosts - excellent footwork from centre Jon Clarke putting Chris Pennell into the space he needed to send Lemi diving over in the corner unopposed.
The boot of Goode then knocked over a penalty harsh on the burrowing Martin Castrogiovanni, and the Italian's evening got worse moments later when he flung himself into tackling Semisi Taulava - referee JP Doyle ruling that he had failed to use his arms in the challenge and issuing a yellow card.
Leicester fly-half Toby Flood was being comfortably outplayed by veteran counterpart Andy Goode in front of watching England coach Stuart Lancaster, and his first attempt to put the Tigers on the board fell short of the target.
On the stroke of half-time, Leicester gave themselves hope when Dan Bowden expertly delayed his pass to Matthew Tait, who ghosted inside his man to provide Scott Hamilton with a routine finish.
Goode blotted his copy-book as Hamilton touched down with a knee-drop that was picked up by referee Doyle, and the former Tiger looked on from the sin bin as his successor Flood fell short again both with the conversion and with the penalty re-start to leave it 14-5 at the break.
The absence of Goode was immediately apparent in the second period with deputising kicker Chris Pennell missing a pair of routine penalties and negating more determined Warriors work up front, but Leicester failed to produce at the other end.
Tom Croft's low-key return to action ended with Julian Salvi's 53rd-minute introduction, and more fresh legs in the visiting pack helped earn a penalty try before the hour mark - Dan Cole and Marcos Ayerza entering the fray to help annihilate the Worcester scrum on their own 5m line.
Flood's conversion from in front made it 14-12 and set up an intriguing final quarter and tempers soon frayed, with Matt Smith clashing with Alex Grove and Flood appearing to spear tackle Goode, who was then wayward with a relatively easy penalty.
With eight minutes remaining, Flood had the chance to snatch it for Leicester after Pennell's flailing arm had caught Mathew Tait square on the nose - but again the England hopeful was inches short of the crossbar.
Typically, Leicester refused to accept defeat, forcing a turnover deep in their own territory which the bloodied Tait ran downfield to spark a move that resulted in another 5m scrum.
Ayerza seemed to initially miss his bind and Worcester may claim the Tigers began pushing before Ben Youngs' put-in, but Doyle saw fit to award a second penalty score from a close-range set-piece and decide the game in favour of Leicester.
Source : http://www1.skysports.com/rugby-union/news/12547/8380825/Leicester-bagged-a-remarkable-19-14-comeback-win-at-Worcester-with-a-controversial-penalty-try