Sunderland’s hitman has kept their hopes of survival alive this season.
The former Tottenham and West Ham man has netted 14 Premier League goals in 30 appearances, despite turning 35 in October later this year.
His age has not held him back though, as Defoe has regained his place in Gareth Southgate’s England team.
And Manchester United face the task of keeping him quiet today when they travel to The Stadium of Light (1.30pm).
Jermain Defoe has 11 more Premier League goals than Sunderland's next highest scorer this term
Similarly, 35-year-old Zlatan Ibrahimovic has excelled at Old Trafford and only suspensions have kept him out of team.
Defoe has avoided injuries throughout his career due to his professional approach, with a move back to West Ham possible should Sunderland go down.
However, Mourinho feels he could still do a job at a club as big as United.
“If you look at Zlatan, why can’t the top teams look at Jermain,” Mourinho said.
England squad during Jermain Defoe's last start
Tue, March 21, 2017
Click to reveal the England squad during Jermain Defoe's last international start, an 8-0 thrashing of San Marino in 2013
Get Quotes on Home Insurance
1 of 24
This is the England squad from Jermain Defoe's last international game in 2013
If you ask me, can he play at the top level of the Premier League again, for one more season? I say yes
“A guy that scores goals. A guy that doesn’t have important injuries during the season.
“A guy that has an ID with many many years but doesn’t look like that on the pitch.
“So if you ask me, can he play at the top level of the Premier League again, for one more season? I say yes.”
Defoe was linked with a switch to United around a decade ago but the Sunderland star has since claimed Louis Saha’s arrival contributed to him not joining.
While the England international has a prolific record in the Premier League, Mourinho is chasing top-class stars in their prime this summer such as Antoine Griezmann and Romelu Lukaku.