The Cameroon international allowed Thiago Almada's soft free-kick to skip past him the day after being called "one of the worst goalkeepers" in United's history in a pre-match spat involving the club's former midfielder Nemanja Matic, now with Lyon.

Teenage defender Leny Yoro equalised just before half-time and Joshua Zirkzee's header in the 88th minute looked to have won the game for United at Groupama Stadium.

But Onana failed to hold Georges Mikautadze's low shot deep into stoppage time and Rayan Cherki poked home the rebound, leaving the tie in the balance ahead of the return clash at Trafford next week.

United manager Ruben Amorim was quick to defend Onana and turn his attention to the second leg.

"It can happen. If you play football, and we play a lot of games, you can make mistakes," he said. "There is nothing I can say to Andre in this moment that will help."

"We have one more game to change everything and that should be our focus," he added.

United's ability to rebuild a squad in danger of the club's worst top-flight finish since relegation in 1974 likely hinges on sealing a return to the Champions League.

Winning the Europa League is the only way they can qualify for the elite competition. Failure to do so is predicted to cost United at least £100 million ($127.6 million) at a time when the club's financial headroom is already minimal.

In a measure of how far both clubs, particularly United, have fallen, this was their first meeting since the last 16 of the 2007-08 Champions League.

Back then, both were at their peaks. United went on to win their third European crown. Lyon scooped the last of seven consecutive French titles.

Perhaps no player has encapsulated United's domestic woes this term more than Rasmus Hojlund, whose five goals in Europe outnumber the three he's managed in the Premier League.

The Denmark striker scuffed an inviting chance horribly wide from Patrick Dorgu's cut-back as United gradually began to threaten, with Lyon defender Moussa Niakhate getting a key touch to divert a crisp Bruno Fernandes effort over the bar.

- Onana the centre of attention -

Any momentum United had built dissipated when Onana failed to keep out Almada's free-kick. The goalkeeper was already in the spotlight after Matic's jibe.

The ex-United midfielder's stinging rebuke came in response to Onana claiming the Red Devils were "way better" than their opponents, comments that Amorim insisted were taken out of context.

Having loudly jeered his every touch, Lyon fans revelled in Onana's misfortune as he allowed Almada's curling set-piece to bounce off his gloves and nestle in the far corner.

United equalised at the end of the half as Manuel Ugarte hooked the ball back into the box after Lucas Perri punched away Fernandes' free-kick, and Yoro glanced home his first goal for the club.

Alexandre Lacazette sliced wide moments after coming on early in the second half following brilliant work from Mikautadze, who weaved past a series of defenders.

Corentin Tolisso pierced the United defence but shot tamely at Onana. Perri had to react sharply to tip over from Garnacho as the Argentine connected with Dorgu's cross.

Casemiro headed the resulting corner narrowly wide before Lacazette blazed over another good chance for Lyon, but the drama was far from complete.

Zirkzee powered a header past Perri after a brilliant ball in from Fernandes only for United's joy to be cut short in the fifth minute of added time when Cherki pounced on another Onana handling error to level.

"I think we deserve even better than a draw. We played really well, but we know there is a second leg to come and we will go there to win, that's all," Cherki told Canal Plus.