A Hakan Calhanoglu penalty gave Inter Milan a 1-0 victory over Arsenal in the Uefa Champions League on Wednesday, as the Italian champions remain undefeated in the competition this season and sit fifth on ten points at the midway point of the new league phase format.

"I think we played a great game against a strong side who play with great intensity," said Inter coach Simone Inzaghi.

Arsenal, on the other hand, experienced defeat for the first time in Europe this season and lie three points and seven places behind their opponents.

The match at the San Siro looked set to go into the break goalless until a penalty was signalled against Mikel Merino after Mehdi Taremi's flick deviated the ball into the Arsenal player's raised hand from close range.

"We were very harshly done by," Arsenal boss Mikel Arteta said. "There is no deflection, nothing you can do in the box – so can he get away from it?"

Calhanoglu stroked home the resulting spot-kick three minutes into first-half injury time.

Yann Sommer and Denzel Dumfries combined on the line to deny Gabriel Magalhaes a leveller shortly before the hour.

Arsenal cranked up the pressure in the second half but were unable to break down Inter's solid defensive block as the Premier League side fell to a second defeat in four days. (AFP)