The former Arsenal captain, who returned to London after three years in Barcelona to join Chelsea last summer, is closing in on his first Premier League title.
The Blues are 10 points clear of the Gunners and victory at the Emirates Stadium would mean three more points would secure the title, points which could come next Wednesday at Leicester.
Mourinho said: "Frank Lampard played at Stamford Bridge (with Manchester City) without any kind of problem and with a good reception
I don't see a reason for Fabregas not to have the same at the Emirates.
"But, if he has some bad reactions, I think he's one of the players who is more than ready.
"He played in Barcelona with an Arsenal shirt
Why can't he play at the Emirates with a Chelsea shirt? I don't see a problem."
Arsenal, for whom Fabregas made more than 300 appearances in eight years, reportedly opted out of their buy-back option when it became apparent he could leave the Nou Camp and Mourinho moved swiftly.
The Portuguese added: "I know why he chose Chelsea
I don't know why he didn't choose Arsenal.
"I can't speak about his time at Arsenal, the decision that made him leave, the decision that stopped him going back
I don't know if it was the manager's (Arsene Wenger's) or if it was his decision
I really don't know.
"I just know that we promised him we'd build a team very adapted to his style of play
That he was going to be an important player in our project.
"And that, normally, good projects always end with titles
He was looking for that
That's all I can say."
Fabregas and Diego Costa, who also joined last summer, have been key to Chelsea's title charge, with the playmaker laying on assists for the striker.
Costa could be fit for Sunday's match and displace Didier Drogba in the starting XI, while Loic Remy (calf) is definitely out.
"Didier for sure is good, is fine
Remy, not for sure
And Diego, let's make a decision tomorrow," Mourinho said.
Dominic Solanke is in reserve, having missed Chelsea's under-21 team match on Thursday, and will be on the substitutes' bench as back-up to Drogba if Costa is not fit.
Costa has scored 19 Premier League goals this season, including one in the 2-0 win against Arsenal in October.
But Costa has missed the last two matches - wins against QPR and Manchester United - after a recurrence of the hamstring problems which have plagued him.
"He's a very important player for us, but the reality is we are coping with the difficulties of every match without him," Mourinho added.
"We played amazingly well during the most part of the season, scoring a lot of goals and controlling games very well through the quality of our possession.
"In the last period we are more strategic, less artistic, but we are having results
I would love Diego to be back, but I trust the other people."
Eden Hazard was also on target in the autumn home win over Arsenal.
The Belgium playmaker is expected to be crowned PFA Player of the Year on Sunday, but Mourinho insists collective honours are more important for Hazard.
The Blues boss also played down the prospect of Hazard moving to Real Madrid after the 24-year-old's idol Zinedine Zidane, now a coach at Real, lauded him this week.
Mourinho said: "We just signed a new contract with him (until 2021)
We didn't put a gun to his head
He had a lot of time to think about it.
"He made a commitment for the future of the team, signing a very good contract
I don't think he's interested in going."
Mourinho recently said every player has a price.
Asked to put a figure on Hazard, he said: "That's a good question
I have my idea about it."
Mourinho has an unbeaten 12-match record against Wenger, but played down a personal rivalry.
"For me, the achievement is to win on Sunday," Mourinho added.
"Matches are isolated events
No relation with the previous one or the next one.
"I respect everyone
He's not my rival."
Mourinho's record against Wenger means to many the title is inevitably heading to Chelsea, but the Blues manager is focused on the mathematics.
"We need eight points," he said, dismissing the alternative two-win scenario.
Despite their commanding lead, Mourinho insists his side have been challenged this season.
Mourinho said: "If we look to the last couple of months, it couldn't have been harder
Everything was difficult."
A long-running rivalry with Wenger turned physical at Stamford Bridge earlier this season when the Frenchman pushed his adversary.
Asked how hard Wenger had pushed him, a laughing Mourinho said: "How hard? Top question
But because I'm always honest in my answers, I cannot answer."
Source : PA
Source: PA