|Connacht (0) 20|
|Tries: Masterson, O'Mahony Cons: Carty 2 Pens: Carty 2|
|Ospreys (24) 24|
|Tries: Biggar, John, Webb Con: Biggar 3 Pens: Biggar|
Ospreys hung on to beat Connacht but failure to get a bonus point victory cost them a home Pro12 semi-final.
The Welsh side will face Munster away in the semi-finals next Saturday after failing to add to the three tries they scored in the first half in Galway.
Dan Biggar, Ben John and Rhys Webb all crossed but a vital fourth try was disallowed before the interval.
Connacht came back strongly with Eoghan Masterson and Denis Buckley tries and face Gloucester in a European play-off.
Despite failing to secure a top-six finish, Connacht could still gain a place in Europe's top tier but must win a play-off against the English side and then win another play-off against a side from the French Top 14.
Failure to secure the all-important bonus point proved crucial for Ospreys as Glasgow's late flurry of tries against Ulster denied them a top-two finish.
Ospreys started the day on top of the Pro12 table but slipped to third after Glasgow and Munster both managed bonus-point victories at home.
They were left to rue Eli Walker's disallowed try for a knock-on in the last minute of the first half.
Ospreys had a strong wind advantage at the Sportsground in their favour in the first half and Biggar opened the scoring with a fifth minute penalty before converting his own try after 16 minutes.
He crossed under the posts after the Connacht scrum collapsed and Ben John picked a great line to send Biggar over for an easy score.
John found some great running angles to punch holes in Connacht's midfield and added their second try after 25 minutes with Rhys Webb adding a third try two minutes later.
Wing Eli Walker though he had grabbed the precious bonus point for Ospreys just before half time after being released by Webb, but on review the try was ruled out as he had lost control of the ball when diving for the line.
Connacht came back strongly in the second half with the wind at their backs with two Jack Carty penalties finally getting the home side on the scoreboard.
After going through a series of attacking lineouts, Eoghan Masterson was shunted over the line for Connacht's first try and Denis Buckley added a second in stoppage time, but it wasn't enough to push Connacht into the top six.
Connacht: T O'Halloran; F Carr, R Henshaw, B Aki, M Healy; J Carty, K Marmion; D Buckley, T McCartney, R Ah You; A Browne, A Muldowney; J Muldoon (c), E Masterson, E McKeon.
Replacements: J Cooney for Marmion (20), M Swift for Browne (60), F Bealham for Ah You (64), M Swift for E McKeon, S O'Leary for Healy (69).
Not used: D Heffernan, G Naoupu, M Nikora.
Ospreys: D Evans; H Dirksen, B John, J Matavesi, E Walker; D Biggar, R Webb; N Smith, S Baldwin, D Arhip, T Ardron, A Wyn Jones (captain), J King, J Tipuric, D Baker.
Replacements: A Jarvis for Arhip (54), D Lydiate for King (60), J Spratt for Evans (64), S Parry for Baldwin (75), J Spratt for Matavesi (80).
Not used: SM Thomas, R Thornton, T Habberfield, S Davies.
Referee: Marius Mitrea (FIR)