Gomis netted the quickest hat-trick in the competition's history and added a fourth later, helping Lyon reach the knockout phase for the ninth year in succession as they leapfrogged Ajax Amsterdam into second place in Group D by virtue of a better goal difference.
"I'm not a hero," Gomis who had not found the back of the net since mid-October, told reporters.
"It's a collective performance. After they had [Jerko] Leko sent off [midway through the first half] I had a lot of space, I just had to apply myself."
Gomis also became only the seventh player to hit four in a Champions League game, joining an elite group that includes Lionel Messi and Marco van Basten.
Lyon's chances looked over when they went a goal behind. They had needed a big win and for Ajax to lose at home to Real Madrid to overturn a seven-goal deficit.
"We thought we had a chance, albeit a small one. We had prepared well and last night we watched Olympique de Marseille's comeback [a 3-2 win at Borussia Dortmund] on TV," he was quoted as saying by UEFA.com.
The achievement, however, had not yet sunk in after the game. "It is surreal, extraordinary," coach Remi Garde told reporters.
"It is perhaps one of the Lyon games that gave me the most emotion," said club president Jean-Michel Aulas, who praised Garde for keeping the team focused before a game that had looked something of a lost cause.
"I think of Remi Garde, who managed to mobilise the team. They managed to stay focused while everyone predicted we would be knocked out," he said.
France forward Jimmy Briand, who scored one and created two, echoed his president's point of view.
"Before the game we were the only ones who actually believed we could do it. I mean the coach, the players, the president and the backroom team," he said.
"We believed it could happen, we came here, and it did happen. At half-time we saw that it was 2-0 to Madrid in Amsterdam and we said we have to give this everything."
