Ulster looked to maintain their six-point advantage as they hosted defending European champions Toulouse at the Kingspan on Saturday.
Ulster beat Toulouse in France a week earlier by six points to take the lead into the second leg of the Heineken Champions Cup Round of 16 tie.
It was a result that Keith Wood deemed 'one of the great victories in Ireland's provincial treks over to France', and Ulster hoped for a repeat performance at home.
Toulouse started off well, with an early penalty to narrow the overall lead. Both sides were subsequently reduced to 14 men for 10 minutes each, as Robert Baloucoune and Dimitri Delibes were sin binned within three minutes of each other.
However, Ethan McIlroy extended the Ulster lead moments after Toulouse's yellow card with a try out wide, which John Cooney converted.
With both sides trading penalties and keeping the game close, French stars Romain Ntamack and Anotine Dupont roared to life to open the game up.
A Ntamack break went to Dupont who set Thomas Ramos away for the try to regain the lead on the night.
That would not be the end of Ntamack's impact on the Ulster defence, though, as shortly after he intercepted a pass inside his own half to run under the post and take the lead in the tie overall.
With their backs against the wall late in the first half, Ulster dug deep to get back in the match. With the penalty advantage, a cross kick from Billy Burns put McIlroy in for hi second try with a spectacular catch and finish in the corner to regain the lead overall, despite trailing by three in at half time.
While the second half had much less movement on the scoreboard, it was not without action. Cooney added two penalties to Ramos' one, in order to level proceedings on the night, but Ulster remained six points ahead.
However, Ulster were fortunate on a few occasions to not see a card of some sort, before Tom O'Toole was red carded for a shoulder to the head of Toulouse's Anthony Jelonch.
It would be the biggest moment of the match, as Ulster were unable to defend their line with just 14 men, and Dupont would score late in the half to take Toulouse to a one-point overall lead after the conversion.
Ulster were unable to get the single score that they needed in the final minute of the match, and Toulouse managed what no other team have done this season in Europe: beat Ulster in Belfast.
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