Greville on song to shock Saffrons
Westmeath, who had to play with only 14 men for 46 minutes, pulled off the first shock of the summer when they fought back to beat Antrim in Mullingar.
Wind-assisted Antrim looked the more accomplished team in an often-ragged first half.
Neil McManus was a dominant figure at centre half-back, while Liam Watson was causing plenty of problems for the home rearguard.
Westmeath's woes were compounded on the half-hour mark when corner-back Conor Jordan, who had been booked in the 16th minute along with Watson after an unseemly squabble which saw a mentor from both players cautioned, was shown the yellow card for the second time.
The Glensmen were well worth their five-point interval lead -- 0-8 to 0-3.
McManus increased Antrim's lead within two minutes of the resumption, but a fired-up Westmeath continued to plug away, with defenders Paddy Dowdall, Adam Price and Paul Greville rallying their colleagues to great effect.
Further forward, Niall O'Brien -- one of two minors in the winners' side -- was on song from frees, having taken over the role from an off-colour Brendan Murtagh.
Murtagh's first point from play had his side on level terms for the first time in the contest, however, (0-11 apiece) with 11 minutes to go.
Three minutes later, Antrim substitute Conor McCann nudged the visitors ahead within seconds of his introduction.
A fine point from veteran Westmeath full-forward John Shaw levelled the contest, and a neat point from Niall O'Brien -- moments after Antrim looked to have solid claims for a free -- and a great long-range free from Murtagh put the maroon and whites two points to the good with just a minute of normal time remaining.
Antrim tried to manufacture a goal from a '65' deep in added-time but a resolute Westmeath defence held firm and now meet Galway in a repeat of last year's provincial quarter-final where they put it right up to the Tribesmen for over three-quarters of the game.
Scorers -- Westmeath: N O'Brien 0-8 (6f), B Murtagh (1f), F Boyle 0-2 each, A Clarke, J Shaw 0-1 each. Antrim: L Watson 0-4, N McManus (2f), S McNaughton (1f) 0-3 each, B McAuley, C McCann 0-1 each.
Westmeath -- S McGovern 6; C Jordan 5, A Price 7, P Fennell 6; P Dowdall 7, A McGrath 6, P Greville 8; A Clarke 6, J Clarke 6; B Murtagh 6, F Boyle 7, R Greville 6; N O'Brien 7, J Shaw 6, E Price 6. Subs: D Fennell 6 for Boyle (64), P Gilsenan for R Greville (70 + 3).
Antrim -- DD Quinn 6; J Kerr 6, C Carson 6, A Graffin 6; M Gettens 6, N McManus 7, N McAuley 6; B McAuley 6, P Shiels 6; M Herron 6, B McFall 5, E McCloskey 5; D Hamill 5, L Watson 7, S McNaughton 7. Subs: K Stewart 6 for Hamill (47), PJ O'Connell 6 for Herron (57), C McCann 6 for McFall (62), S McCrory for Kerr (68).
Ref --A Stapleton (Laois).