Defoe has been sidelined for a month after hobbling off against West Bromwich Albion, since when his side have risen above Chelsea to third place in the Premier League thanks to an incredible burst of scoring by Wales winger Gareth Bale.
Victory over Arsenal at White Hart Lane would put Tottenham seven points clear of their neighbours in the race for Champions League qualification with 10 games remaining and the return of England striker Defoe would be a huge boost.
"Jermain trained with the team the last two days and so hopefully he will be available for selection if he trains again tomorrow," manager Andre Villas-Boas told reporters at the club's training ground.
"He's definitely a contender for the game."
Defoe enjoyed a superb first half to the season, scoring 10 league goals, but Tottenham have recently been reliant on the goals of Bale who grabbed another two in a 3-2 victory over West Ham United on Monday to take his league tally for the season to 15.
Eight goals in his last six matches in all competitions has inevitably led to suggestions that Bale will be sought by Real Madrid or Barcelona at the end of the season but Villas-Boas said he could achieve his ambitions in England.
"For a player to develop to his full potential it can happen in this league because it's the best in the world and Gareth has that in mind," Villas-Boas said.
"We want to keep our biggest assets to achieve our objectives. This season it's to reach the Champions League and next season you never know what team we can build if we achieve that."
NO BALE PLANS
Arsenal manager Arsene Wenger said he was making no special provisions to stop Bale.
"We don't plan for anybody," the Frenchman explained. "He is not a subject of our worries for the next two or three days.
"We just want to prepare. We have great players in our team and it would be a complete mistake to focus on any player from Tottenham."
After a mediocre start under Villas-Boas, who was sacked a year ago by Chelsea, Tottenham have lost just once in the league since a 5-2 hammering by Arsenal in mid-November, a run that has put the club in a strong position to claim a top-four finish.
However, they were also poised to finish above Arsenal last season before another 5-2 defeat signalled a slump that meant they ended up fourth, missing out on the Champions League as Chelsea went on to lift the European crown despite finishing sixth in the table.
Villas-Boas said the result of Sunday's game at White Hart Lane would not necessarily prove decisive.
"It won't be decided this weekend, even seven points is still recoverable for a team like Arsenal," he said. "It's very tight bearing in mind the amount of games there are still to be played.
"But we know the importance of the fixture and how it can impact the mood of both clubs. There is a pressure on both sides for this game. It will be a special one."
Victory for Tottenham would also put them two points behind second-placed Manchester City, who play on Monday at Aston Villa, and Villas-Boas said his side could still target the runners-up spot behind runaway leaders Manchester United.
"It's difficult because City have the experience of winning the league [last year] but they have to come to White Hart Lane and if we receive them still within a margin of five points then we can be a threat to them," he said.
"But our focus is on the gaps to the teams behind us more than anything else."
Villas-Boas also confirmed that Younes Kaboul was still at least two weeks away from a near season-long absence because of knee trouble.
