Chelsea met Inter Milan at the Rose Bowl in Pasadena in July and won the game 2-0. Now the sides meet in Champions League action at the San Siro this evening with Mourinho up against his former club for the first time in a competitive fixture.
Chelsea, now coached by former AC Milan boss Carlo Ancelotti, will be looking to take some kind of advantage back to Stamford Bridge for the return leg of their last-16 tie.
Man on a mission: Chelsea's John Mikel Obi (right) wants a win in Milan
Mikel, brought to Chelsea by Mourinho, admits he has a soft spot for his former coach but that will mean nothing when he crosses the white line tonight.
'Mourinho is the man who brought me to Chelsea and this is the first time I will play against him, though we played in a friendly and won 2-0,' said Mikel, who will play an important role tonight as the Blues seek to nullify the threat of Inter's midfield trio Sulley Muntari, Dejan Stankovic and Wesley Sneijder.
'It is a soft spot but we have to do what we did in the friendly and win the game.'
When asked to compare Mourinho with his current coach, Mikel was full of praise for both men. The Nigeria midfielder added: 'They are both very good managers and I am really pleased to work under both of them.
'Ancelotti has come in and brought a different mentality to the way we play, playing a diamond system and I think it has been really effective. We have to just keep supporting the manager and playing to his instructions.'
Old pals: Mikel Obi trains under the gaze of Jose Mourinho, then Chelsea manager
Ancelotti must deal with a defensive crisis, but the Italian is confident Juliano Belletti can fill the void at left-back. The Brazilian utility player has been out for a month with a knee injury, but is set to come in for the injured duo Yury Zhirkov and Ashley Cole.
Zhirkov is out with a calf problem and Cole is sidelined with a broken ankle, while Paulo Ferreira, who has deputised at left-back before, is not registered for Champions League competition.
'Definitely it's a problem, we are missing two important players,' Ancelotti conceded.
'Belletti is back, he has been training all week and has been training well. We will definitely find a solution, however, Ashley Cole and Zhirkov are going to be missed.'
It is the first time Ancelotti has returned to the San Siro since switching northern Italy for west London last summer. He refuted claims that he believed most Italian supporters would want Chelsea to triumph.
'I never said this, now I work for this club I will try my best for this club,' he said. 'Italian fans are interested in this game because it's very interesting for football fans, it's a very important game, two strong teams playing.
'I don't know if Italian fans support Chelsea or not, I am not interested for this, only that Chelsea do the best in this game.'
Mourinho: I'm still England's main man, Carlo! Special One taunts rival AncelottiLampard: I nearly joined Inter but mum told me not to forget debt to ChelseaJohn Terry and Chelsea beware: Here comes Inter dangerman Diego MilitoCHELSEA FC