Ospreys (6) 15
Pens: Hook 5
Leicester (3) 9
Pens: Hougaard 3
Tigers skipper Martin Corry celebrates topping Heineken Cup Pool Three
The Ospreys won the battle, but Leicester won the Heineken Cup Pool Three war at Liberty Stadium to ensure their place in the quarter-finals.
Ryan Jones' side must now await results from Sunday's tournament clashes to discover if they will make the last eight after failing to win by more.
Ospreys led 6-3 at the break as James Hook won his kicking duel with opposite number Derick Hougaard.
Hook kicked three more penalties in the second half, Hougaard two for Tigers.
The visitors' tactics of slowing the game down in the face of the threat posed by the Welsh side's attack paid dividends as they did enough to hold on to top spot in the pool by securing a crucial losing bonus point.
The Ospreys were forced into a late reshuffle ahead of kick-off against Leicester after Lee Byrne was ruled out with a recurrence of ankle problems.
Ospreys boss Sean Holley opted to switch Gavin Henson from inside centre to full-back and re-jig his midfield with Andrew Bishop taking over the number 12 jersey and Tommy Bowe coming in at 13.
That left a hole on the wing filled by Jonny Vaughton, whose place among the replacements was taken by flanker Steve Tandy.
The hosts took an early initiative, skipper Ryan Jones making ground on several occasions in a period in which Hook kicked two penalties.
Martin Corry's men hit back as their tactical kicking paid dividends, fly-half Hougaard kicking a 14th-minute penalty having used his boot to good effect out of hand.
However, the South African then missed a penalty attempt and sent a drop-goal attempt wide.
The Tigers found themselves down to 14 men after 30 minutes, the patience of French referee Christophe Berdos finally wearing thin following earlier warnings as centre Toby Flood was sin-binned for kicking the ball away from the back of an Ospreys attacking ruck.
When Geordan Murphy barged Shane Williams off his kick-and-chase path, the hosts opted for an attacking line-out instead of going for the posts.
That led to an attacking scrum and another penalty award only for Ryan Jones' tap-and-pass to be knocked forward and a counter-attack ending with Hook holding on too long in a tackle and being penalised.
The Ospreys were clearly the better attacking team in the opening period, but the Tigers' defence proved equal to the task and the hosts led 6-3 at the break, having survived Flood's absence without conceding a penalty.
Five minutes into the second half, a Mike Phillips kick-and-chase forced Marco Wentzel to concede a penalty and Hook this time made no mistake.
The visitors struck back as the Ospreys fell foul of the ball-killing trap, Hougaard hitting the mark after 57 minutes.
Four minutes later Hook re-established his side's six-point lead only for opposite number Hougaard to strike back.
Seven minutes from the end Hook again hit the mark and the teams ended try-less after 160 minutes of action in the competition this season.
Ospreys boss Sean Holley:
"It is quite a numb dressing room. We hope we have done enough to qualify."
Leicester acting head coach Richard Cockerill:
"We fronted up physically, and we did enough to qualify. I thought the players' attitude was fantastic.
"We've done the job, and although it wasn't perfect, we've won the group and we move on."
Ospreys: Henson; Vaughton, A Bishop, Bowe, Williams; Hook, M Phillips; James, Hibbard, A R Jones, Gough, A W Jones, R Jones (capt), Holah, Tiatia.
Replacements: Nutbrown for M Phillips (69), Bennett for Hibbard (69), Smith for Tiatia (72).
Not Used: Griffiths, Bateman, Tandy, Biggar.
Leicester: G Murphy, Hamilton, Rabeni, Flood, Smith, Hougaard, Dupuy, Stankovich, Kayser, White, Corry, Wentzel, Croft, Woods, Crane.
Replacements: J Murphy for Smith (52), Chuter for Kayser (75), Castrogiovanni for White (62), Kay for Wentzel (61).
Not Used: B Deacon, Youngs, Vesty.
Sin Bin: Flood (29).
Ref: C Berdos (France).