Cavani was the star of the 8-5 aggregate triumph as he followed his first-leg brace with another pair in the eternal city, where he fired the visitors into a first-half lead from a fine Fred pass.

But David De Gea was the standout performer at the Stadio Olimpico, producing fine early saves and then some outstanding stops as United wobbled following quickfire Edin Dzeko and Bryan Cristante efforts.

Cavani rose to head United back level on the night from a superb Bruno Fernandes ball, but Roma gave it their all days after it was confirmed that Paulo Fonseca would be succeeded by Solskjaer's predecessor Jose Mourinho.

Teenage debutant Nicola Zalewski fired home a deflected late effort to seal the spirited hosts a second-leg victory, but it is the Red Devils heading to Poland for a shot at their first trophy since winning the competition in 2017.

Back in action after Sunday's match against Liverpool was called off due to the anti-Glazer protests, Solskjaer named a strong line-up in a bid to halt a Roma side that looked determined to make things difficult.

Fonseca's side started brightly and De Gea produced a superb save to prevent Gianluca Mancini striking home from close range.

The Roma man handled in the build-up but the VAR could not intervene as there was no goal, meaning the resulting corner went ahead and ex-United playmaker Henrikh Mkhitaryan headed wide.

De Gea cut out a Rick Karsdorp cross following an uncharacteristic Luke Shaw error as Roma frustrated the visitors, who created precious little but clipped the top of the crossbar with their first opportunity.

Cavani had that chance and coolly lifted over Antonio Mirante, with the 34-year-old's next effort stopped in unorthodox fashion by the back-up Roma goalkeeper.

An exceptional Fernandes pass was key to opening the Giallorossi backline, which was forced into a rejig as ex-United defender Chris Smalling limped off around the half-hour mark.

The Serie A side did not look ruffled. Mkhitaryan met a cross with a brave header just wide, with De Gea stopping a Lorenzo Pellegrini snapshot before clutching an attempt from Mancini.

But Roma would be hit by a 39th minute gut punch. Fernandes flicked smartly into the path of Fred, who played Cavani in to fire a thumping 20-yard effort past hapless Mirante.

Mason Greenwood struck across the face of goal and De Gea denied Mkhitaryan during a frantic end to the half, with Fernandes failing with an audacious hooked effort before bending wide.

Solskjaer made two changes at the break and Roma finally beat his inspired goalkeeper in the 57th minute, with Pedro smashing a ball into the ground for Dzeko to head home from close range.

That goal sparked new life into Roma. Just three minutes later Fred was caught overplaying on the edge of his own box, with Cristante swivelling to fire home a superb first-time strike.

United were stunned by the quickfire double and only De Gea prevented them falling further behind.

The 30-year-old denied Dzeko from a point-blank header and then superbly prevented Pedro's fizzing rebound from finding the net.

If De Gea showed his best with that double save, he knew little about the stop that denied Mkhitaryan when meeting a Pedro effort from close range.

United belatedly steadied as Fernandes and teenager Greenwood, making his 100th appearance for the club, had efforts before Cavani settled the nerves.

Fernandes was the provider for the 34-year-old, who got behind to power a low header past Mirante in the 68th minute.

Roma were not done there, though, and Mkhitaryan struck the foot of the post.

That pressure told as substitute Zalewski fired the hosts ahead via a deflection off Alex Telles in the 83rd minute, but United were not to be denied. The damage had been done at Old Trafford.