The visitors trailed 17-7 at half-time but turned the game around after the French side had Paul Willemse sent off in the 41st minute for a high tackle.

As their discipline unravelled, Montpellier would spend a period with 12 men after three second-half yellow cards.

Ulster will now face Clermont away in the quarter-finals.

Both sides were forced into changes before kick-off, with Montpellier losing former All Black George Bridge from the team they had named on Friday.

Ulster, meanwhile, were without Ethan McIlroy which brought Will Addison into the starting line-up, having not originally been involved at all.

The visitors appeared to cope well with the upheaval in the early stages, making a strong start only to be undone by a strong Clement Doumenc turnover.

Montpellier's superiority at the breakdown would become a running theme of the first half.

When the Top 14 strugglers took the lead, Ulster had a huge hand in gifting them the opening score.

Addison knocked on behind his own try-line when chasing back a long kick, giving Montpellier a scrum five metres out.

The French side's power in the close exchanges was to the fore with captain Willemse barging over.

If that was all about brute force, Montpellier's second score was full of guile.

Alex Becognee, who had been a huge thorn in Ulster's side defensively, showed his skills with ball in hand as he popped up a pass for Aubin Eymeri.

The scrum-half still had plenty to do but his measured chip and chase saw him go over.

Ulster were rocking on their heels but Addison's try just before the half-hour mark dragged them back into the game.

Rob Baloucoune had looked set to score himself but was hauled down just short by his opposite number Gabriel N'Gandebe.

While the ball came loose in the tackle, referee Ben Whitehouse adjudged it had gone backwards and Addison scooped up to score.

Montpellier extended their advantage on the cusp of half-time, Louis Foursans knocking over a penalty - but those would be their final points.

Only a minute into the second half, Willemse saw red for his high tackle on Addison and Ulster took control with the extra man.

Just two minutes later, Baloucoune touched down out wide off Stewart Moore's diving pass out of the tackle.

Against only seven Montpellier forwards, Ulster got a real edge off the scrum but the province were initially frustrated as it would be another 20 minutes before they crossed again.

After winning a series of penalties, Ulster used a five-metre tap to set up a rolling maul which, although stopped short, eventually led to replacement prop Scott Wilson driving over.

John Cooney's second conversion gave Ulster the lead and one they did not lose.

In an increasingly bad-tempered contest, Florian Verhaeghe and Vano Karkadze were sent to the sin-bin in quick succession, leaving Montpellier with only 12 men for just over nine of the final 15 minutes.

Moments after Karkadze was yellow carded for coming in at the side of the maul, David McCann claimed a close-range try and Cooney converted.

There was still time before the end for Stuart McCloskey to go over and a penalty try added gloss to the final score, while Montpellier also had N'Gandebe sent to the sin-bin too.

Line-ups

Montpellier: De Nardi; N'Gandebe, Lucas, Cadot, Lam; Foursana-Bourdette, Eymeri; Fichten, Tolofua, Williams; Verhaeghe, Willemse (capt); Becognee, Doumenc, Simmonds.

Replacements: Karkadze, Erdocio, Macharashvili, Duguid, Camara, Carbonel, Dakuwaqa, Tisseron.

Sin bin: Verhaeghe (65), Karkadze (66), N'Gandbebe (81)

Red card: Willemse (41)

Ulster: Addison; Baloucoune, Hume, McCloskey, Moore; Doak, Cooney; Kitshoff, Herring, O'Toole; O'Connor, Henderson (capt); Rea, McCann, Timoney.

Replacements: Andrew, Warwick, Wilson, Sheridan, Izuchukwu, Shanahan, Flannery, Ewers

Match officials

Referee: Ben Whitehouse (WAL)

TMO: Daniel Jones (ENG)