Mourinho was the Chelsea FC manager who gave the young Danish defender his debut back in 2014 in a League Cup tie.
Christensen was subsequently sent out on loan to German side Borussia Monchengladbach for two seasons and returned to the west London club last summer.
The defender has been a regular fixture in the Chelsea FC first team this season and he made a total of 27 Premier League appearances for the west London club.
Christensen is now set to come up against Mourinho’s Manchester United side when Chelsea FC take on the Red Devils in the FA Cup final at Wembley on Sunday afternoon.
And the Danish defender has admitted that he is grateful to Mourinho for giving him his shot in the first team at Stamford Bridge.
Speaking in an interview with Chelsea FC’s website, Christensen said: “He [Mourinho] gave me my first start against Shrewsbury Town and I just remember it was a case of always having to work hard in order to earn your spot in the side.
“I enjoyed that time. The club then gave me the opportunity to go out on loan, but if that hadn’t come up I would have been happy to stay because I liked the way we worked, it was good.”
Chelsea FC are aiming to end the season on a positive note after having struggled to find consistent form in the Premier League this term.
The Blues slumped to a fifth placed finish in the Premier League this term to leave them without Champions League football next season.
MORE: Man United latest news
MORE: Arsenal latest news
MORE: Chelsea latest news
MORE: Liverpool latest news