Amara Diane struck in the 19th minute of the Group A contest and Juninho missed a penalty in the second-half as they collected their first win of the campaign and inflicted Sepahan’s first defeat in the process.
Al Gharafa now move on to four points, although they still trail leaders Sepahan by five with two games to go.
“First of all I'd like to say it was a tough game because Sepahan are a strong team at the Asian level,” said Metsu.
“The first 10 minutes were really dangerous. We had to change the formation but I would like to say that Amara (Diane) played really well for us. This was a pressure match.
“We have another injury to Otman El Assas so that's more problems for us. We also missed a penalty but that's football.”
“I am happy with the players. They gave their best, it is a young team. Results like this are good for the future. It gives us hope.
Sepahan boss Amir Ghalenoei afterwards criticized the referee for disallowing Reza Enayati's early goal but Metsu felt the Iranians should have made more of their chances.
“Every time you lose a game, teams blame the referee,” he added.
“I think it is easy to talk about referees after a game. Also you had many chances to score and did not. So it is not the referee's fault that you missed chances to score.”
Ghalenoei did concede, however, that Sepahan were below par.
“It was a good match, it was a watchable match. I firstly congratulate Mr. Mestu on the win,” he said.
“We tried to make changes but we are not satisfied because we did not put up a quality game. I feel my players were tired too because a lot of travel was involved before arriving here.”