Reports on Thursday night stated a deal was close between the Red Devils and Inter Milan for the Cameroonian goalkeeper, who had interested Chelsea earlier in the transfer window.
United are set to pay an initial £42m for Onana with a further £5m in add-ons set to be part of the deal.
Onana, 27, was part of the Inter team to reach last season’s Champions League final and spent two years with Brazilian winger Antony at Ajax.
The United player talked up his relationship with the goalkeeper and strongly suggested he would like to see his club complete the deal.
“I know him very well, we played together at Ajax,” he told La Gazzetta dello Sport.
“He is a great goalkeeper and a nice person.
“It’s not for me to say [if he will sign], because it’s the club’s decision and not mine.
“I can only say that he is definitely very strong. And that there is a very good relationship between us.”