Inter forward Romelu Lukaku looks in better shape than before, according to his former Belgium assistant coach Thierry Henry.

Lukaku came off the bench in the 58th minute against Porto on Wednesday before netting the only goal in the Nerazzurri's Champions League last-16 first-leg win.

Inter CEO Beppe Marotta had called into question Lukaku's fitness when he told Sky Sport the forward "needs to be in perfect physical shape to deliver" and that "he is not there yet".

But Lukaku, on loan at Inter from Chelsea, provided the perfect response when he lashed home a close-range chance after his initial 86th-minute header had hit the post.

"I am so happy for Rom," Henry said on CBS Sports. "He looks fitter, he looks slimmer, he wants it.

"I think he was disappointed that he didn't start. The only answer you can give is on the field, and he did that.

"Great header. The ball goes inside, great cross, that's what you do. You come on the field and try to make an impact to make sure you can ask your coach questions – 'next time am I going to be in the starting line-up?'"

Lukaku's future remains uncertain having underwhelmed so far during his season-long loan spell with Inter, netting four times in 14 appearances.

However, his return to Chelsea last term was similarly disappointing.

"We had a discussion when he went to Chelsea, and I told him he's going to find it difficult to play at Chelsea," Henry added. "That happened to be the case, because of the way [Thomas] Tuchel liked to play.

"Pressing, you're the nine, I'm the nine, I'm the winger, you're the winger, you have to change. Rom likes to stay where he is. Feed him, play him in early, and he'll try to bully you.

"He was a different type of nine to what Tuchel wanted. Is he going to fit what [Graham] Potter's trying to do? They're struggling enough.

"And what does he want to do? I don't think he wants to go back. That's the main thing. He wants to stay at Inter."