Inter Milan’s Adriano celebrates his goal against Villarreal in Milan on Wednesday. (Reuters)

London: Inter Milan grabbed a slender advantage over Villarreal with a 2-1 comeback victory while AC Milan came away from Olympique Lyon with a goalless draw in the second two quarter finals of the Champions League on Wednesday.

Both ties remain open with Villarreal, enjoying a dream first appearance in Europe’s top club competition, clinging on to a precious away goal scored by Diego Forlan after 45 seconds in the San Siro.

In a high-quality match full of chances, Adriano and Obafemi Martins turned things round for Inter to hand the Spaniards their first away defeat in 12 European matches and leave next week’s return leg nicely poised.

Should Inter advance, they will play Arsenal or Juventus, with the English side holding a 2-0 advantage from Tuesday’s first leg at Highbury.

The second semi-final will feature last year’s runners Milan or Lyon taking on favourites Barcelona or Benfica, who drew 0-0 in Lisbon on Tuesday.

There was an explosive start in the San Siro as Villarreal netted in the first minute and Inter almost equalised in the second.

Uruguay striker Forlan scored on the rebound after Francesco Toldo had parried an effort from Jose Mari, but Villarreal needed a goalline clearance by Javi Venta to deny Adriano moments later.

The Brazilian had more luck in the seventh minute when he converted a pass from Dejan Stankovic to equalise.

Captain Javier Zanetti gave a tireless display up and down the right as Inter cranked up the pressure.

But it was Stankovic on the right who was again the provider as Martins scrambled the second goal in the 54th minute.

Villarreal were not downhearted though, and came close to an equaliser 10 minutes later when Juan Riquelme thumped a free kick against the bar.

“Obviously we’re not happy with the result, but we had a lot of players missing, and I was happy with the performance of the team,” coach Manuel Pellegrini told Spanish state television.

“I’m very optimistic and the tie is still very open. I hope we can win 1-0 in the return leg to see us through.”Six-times winners Milan produced a classic European away performance to prevent French league leaders Lyon scoring for only the third time in 45 games. Lyon badly missed suspended Brazilian playmaker Juninho as Andrea Pirlo and Gennaro Gattuso took control of midfield.Milan also had the clearer chances as Andriy Shevchenko forced goalkeeper Gregory Coupet into three smart saves in the opening period.

“We showed them too much respect in the first 20 minutes and we can consider ourselves lucky to have reached the interval level,” Coupet told reporters.

The result makes the Italians favourites to go through after next Tuesday’s second leg at the San Siro.

Milan gave a typically strong defensive performance as Ligue 1 leaders Lyon failed to score for only the third time in 45 matches.

The French side kept up their unbeaten run in this season’s competition despite failing to score for the first time.

Lyon eventually lifted their game and created their first chance, Brazilian keeper Dida saving well after John Carew had deflected a free kick from Benoit Pedretti in the 26th minute.

Technically superior and better organised, Milan left little room for Lyon’s forwards, with defenders Alessandro Nesta and Kakha Kaladze outstanding.

Coupet again thwarted Shevchenko in the last minute of the first half.

Lyon moved up a gear after the interval and increased the pressure on Milan’s defence.

Midfielder Tiago, who scored twice in the 4-0 rout of PSV Eindhoven in the previous round, had a 56th-minute shot deflected by Kaladze’s back with Dida beaten.

Portuguese Tiago will miss the second leg through suspension after he was booked for a foul on Kaka in stoppage time.