Speaking to ESPN, Paul Mariner is backed former side Arsenal to overcome Southampton en route to reaching the semi-final of the League Cup on Wednesday.
The North Londoners welcome their South-Coast counterparts to the Emirates Stadium tomorrow night as Wenger's side look to move within two matches of a trip to Wembley in February.
Manager Arsene Wenger has regularly named an under-strength XI in this competition and he is likely to do the same against the Saints, who could also name a weakened side due to their participation in the Europa League.
And Mariner, who spent two years at Arsenal back in the 1980s, feels that his old club will triumph against Claude Puel's side.
"I think he [Mourinho] will field a fairly strong side. He needs the win. I'm going for Manchester United," he told ESPN.
"I think even though Arsenal will field a weakened side, I think they'll win the game."
As mentioned, Arsenal beat Southampton this season but it was only by a 1-0 margin.
In fact, they needed a last-minute penalty from Santi Cazorla to see off the Saints, so tomorrow's visitors could prove something of a handful for Wenger and co.