It had been his boot that had given the Chiefs a deserved 9-6 interval lead with three penalties from four attempts and he added fourth after the break. But a magical few minutes at the start of the second half got Stade back into contention and gave them the belief to go on and clinch a place in the last four.

A neat grub kick through by Felipe Contepomi, who spent 10 minutes in the sin-bin for throwing a punch in the first-half, caused problems for the Chiefs and full back Djbril Camara nipped in to cross at the left corner. Two minutes later man of the match Julien Dupuy kicked the first of his two long range penalties of the half and all of a sudden the home side had 14-9 lead.

Dupuy and Mieres swapped penalties to leave the game hanging in the balance in the final quarter at 17-12, but it was the visitors, in only their second season in European competition, who stepped up their game and went looking for the score to keep their hopes alive of reaching the semi-finals.

Naqelevuki ran through five players to cross for his try and at that stage the chiefs looked the most likely to go on and win. They dominated territory and when replacement scrum half Kevin Barrett broke through to the foot of the Stade posts, the scene seemed set for Mieres to win the game on the eve of his 25th birthday.

He dropped back in the pocket, waited for the pass, but then pushed his drop goal attempt wide with two minutes left on the clock. That let Stade off the hook and their determined defence kept them in the game.

With the game seemingly heading for extra-time, Stade mounted one last assault and Dupuy created space in the Chiefs' 22 with a log, cut-out pass and Williams cantered over to break Exeter hearts in the 79th minute.

Stade, who lost the Amlin Challenge Cup final to a last minute try from Gonzalo Camacho for Harlequins, live to fight another round. They will travel to face the winners of Good Friday's second quarter-final between Toulon and Harlequins.