Romelu Lukaku boosted Inter Milan's chances of reaching the Champions League quarter finals for the first time in over a decade after scoring the only goal in Wednesday's 1-0 win over Porto.

Belgium forward Lukaku struck with four minutes remaining of the first leg at the San Siro on the rebound from his own header to decide an absorbing encounter at the San Siro.

Simone Inzaghi's side travel to Portugal next month to decide who will go through to the last eight with a slight advantage thanks to Lukaku's second goal in as many games in all competitions.

The 29-year-old, who has struggled with injury all season, struck his first league goal since August at the weekend and came off the bench in the second half to ensure Inter will have a lead to protect in the second leg as they seek a first quarter-final tie since 2011.

"Winning is the most important thing... I'm focusing on trying to do what's best for Inter," said Lukaku to Amazon Prime.

"I'm pleased for the win, let's hope we can keep it going."

Lukaku stuck as Sergio Conceicao's Porto were playing with 10 men after key midfielder Otavio, in his first appearance since the start of February, was sent off in the 78th minute for two bookable offences.

The Portuguese champions have been a bogey side to Italian teams in recent seasons but will have to turn the aggregate score around if they are to add to the series of Serie A scalps which include Juventus and Roma.

"It's a slight advantage that we'll try to make count against a good, physical team which is used to playing in the last 16 and quarter-finals... It's a great win," said Inzaghi.

"It was deserved for what we did on the pitch, but we know it's not finished here and the second leg will be difficult."

Inter should have been ahead in the 13th minute when Federico Dimarco found Lautaro Martinez with a deep cross, but the Argentina striker sent his header way of the bar.

Five minutes later Hakan Calhanoglu forced a fantastic save from Diogo Costa, the Turkey international playing a one-two from his own corner and whipping a beautifully struck effort shot which nearly went in at the near post.

However, it was Porto who wasted the best chance of a niggly half in the 37th minute after a lovely team move, their first decent attack of the match.

From Otavio's pass Mehdi Taremi played the perfect layoff to Marko Grujic, who should have done better in front of Andre Onana before Wenderson Galeno headed wide with the goal gaping.

Costa then made sure that the teams would go into the break level with another superb stop, this time reacting brilliantly to keep out Alessandro Bastoni's flicked header from Dimarco's inswinging free-kick.

Barella flicked just wide before Porto missed two more great chances to take the lead.

In the 54th minute, Taremi shot weakly at Onana at the end of a lightning break led by his striker partner Pepe, and then three minutes later Onana twice save Inter's bacon in the space of seconds.

Milan Skriniar did well to block Zaidu's low shot before former Cameroon goalkeeper Onana grasped at the Porto left-back's second effort and then recovered in time to stop what looked like a certain Taremi goal.

"We had plenty of opportunities to score. We created situations in second half where we should have been more aggressive, because we were lacking in the finish," Conceicao later told reporters.

"Inter played well, but if we look at the chances at the end of the match, I think we should have got a different result."

Lukaku almost immediately replaced the disappointing Edin Dzeko and in the 72nd minute the Belgium striker almost laid on the opener for Martinez, who just couldn't quite meet an inviting low cross as he slid into the six-yard box.

Just as the match looked destined for a goalless draw despite Otavio's dismissal, Lukaku headed Nicolo Barella's cross against the post before slotting in the winner on the rebound.