Atletico Madrid's Antoine Griezmann (R) celebrates after scoring his second goal past Galatasaray's goalkeeper Fernando Muslera (L) during their Champions League Group C soccer match in Istanbul, Turkey, September 15, 2015. [Photo/Agencies]

ISTANBUL - Two first-half goals from Antoine Griezmann gave Atletico Madrid a strong start to their Champions League campaign with a 2-0 away win over Galatasaray in their opening Group C fixture on Tuesday.

Griezmann put the visitors ahead in the 18th minute when Juanfran sent in a cross from the right and the French international fired the ball past an outstretched Fernando Muslera in the Galatasaray goal.

Atletico doubled their lead with a second goal from Griezmann in the 25th minute when Diego Godin headed a cross from Koke back across the goal for the winger to knock the ball into the net from close range.

The home side's goal opportunities were few in the first half. Atletico keeper Jan Oblak was tested in the 29th minute, pushing the ball behind for a corner after a long-range shot from Wesley Sneijder. Umut Bulut and Jason Denayer both had opportunities late in the first half but headed wide.

In the second half Galatasaray raised the pressure on the Atletico goal while Atletico sat back and focused on maintaining their lead.

Lukas Podolski shot wide from the edge of the penalty area in the 51st minute and Sneijder fired in a shot which missed the target two minutes later. An opportunity fell soon after to Selcuk Inan who also fired wide of the post.

But Atletico kept their lead intact despite the pressure and Griezmann had a chance to complete his hat-trick in the 86th minute but with only the keeper to beat, Muslera blocked his shot.