The summer signing is expected to shrug off a groin injury suffered on international duty with Cameroon.
Onana went off with a groin problem against Mauritius last Friday and was withdrawn from the squad to face Libya on Tuesday night.
United have been plagued by fitness problems this season.
And boss Ten Hag would have had little choice but to hand Altay Bayındır his debut this weekend if Onana was still struggling.
Turkey ace Bayindir cost £4.3million from Fenerbahce in the summer.
But journalist Fabrizio Romano suggests Onana will make United’s line-up when the Premier League resumes this weekend.
Nonetheless, Cameroon football chiefs confirmed the ex-Inter Milan star, 27, was out of Tuesday’s World Cup qualifier.
They said in a statement: “The medical imaging carried out by the doctors of the national selection revealed a condition in the pubis.
“Fecafoot (Cameroon FA) wishes a speedy recovery to the Cameroonian international.”
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Meanwhile, Bayern Munich are reportedly showing surprise interest in United’s out of-favour centre-back Raphael Varane.
It’s suggested the Bundesliga champions and leaders will monitor the situation but believe his salary would be a huge stumbling block.