“In the first half he was telling us he was feeling something in his calf but in another leg,” Unai Emery explained afterwards. “I don’t know how he’s going to recover.
“Hopefully in a few days he can recover. But of course we must be careful with him as well.”
Onana made his return to the Villa side at the City Ground, having recovered from a knock that saw him miss the defeat to Fulham last weekend.
With the second leg falling after the Spurs game, it is possible that the Belgium international is not risked on Sunday to give him more time to prove his fitness for the big European decider.
Villa are currently fifth in the Premier League table and are on course to qualify for the Champions League, regardless of the outcome from their Europa League journey.
Emery’s side have an eight-point advantage over sixth-placed Brighton which means a return to Europe’s top table could be sealed as early as this weekend, depending on results elsewhere.
Tottenham won their first league match in 2026 against already-relegated Wolves last weekend, but the result was not enough to lift them out of the bottom three due to West Ham’s win over Everton.