Witsel was also interesting United before he committed to Borussia Dortmund this week.
And agent Paul Stefani lifted the lid on United's attempts after the deal was close.
"I know from a very good source that José Mourinho said he wanted Witsel, but not in the first place. N'Golo Kanté topped his list.
"In the end Axel said: 'Do me a favor and get it done as soon as possible, because I really want to go to Dortmund'."