The Italian, who missed Monday's 1-0 win at Wigan Athletic that restored City's three-point lead at the top of the table, is in the frame for the tricky game against third-placed Spurs and defender Micah Richards is back too.
"Mario is OK, he did [training] yesterday," Mancini told a news conference.
City hammered Spurs 5-1 at White Hart Lane in August but since then Harry Redknapp's men have lost only once in the league and turned into title contenders, winning many admirers with their attractive brand of football.
Mancini said the August thumping would have no bearing on Sunday's match because meeting as title rivals was different to playing each other at the start of a season when results can be strange.
"It's better to lose one time 5-1 than five times 1-0," he said.
"We played five months ago, it was totally different. When you start the season anything can happen because all the squad are not ready to play 100 percent. Every team needs four, five, six games to be confident."
Mancini added Spurs could win the title but that defeat by his team would "maybe" end the London club's challenge.
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He joined the band of admirers of Tottenham's playing style but fell short of Manchester United manager Sir Alex Ferguson's assessment last month that Redknapp's team were the best team to watch at the moment.
"They play the best football probably - after us," the Italian said.
"For me, the best football [is played by] Swansea, they play very well," he added, referring to the promoted side from Wales.
City are three points clear of champions United at the top of the table with 51 points from 21 games, while Spurs are five points behind Sunday's opponents.
Having torn apart teams with their relentless attacking for the first half of the season, City had suffered a mild wobbly patch at the start of this year before answering their critics with a gritty 1-0 win on a cold Monday night in Wigan.
They managed it without suspended centre-back Vincent Kompany and influential midfielder Yaya Toure, who along with brother Kolo is on Africa Cup of Nations duty with Ivory Coast.
"It was important [the Wigan win] but we have another four or five games in this situation," Mancini said.
