Defoe, who joined Portsmouth from Tottenham for 7.5 million pounds ($11.19 million) a year ago and re-joined the London club this month for a reported 15 million ($22.37 million), rescued Spurs with a 70th minute strike after David Nugent had put the vistors ahead 11 minutes earlier.
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The draw means the five teams at the foot of the table all have 21 points with Spurs moving out of the relegation zone on goal difference at the expense of Middlesbrough while also sending West Bromwich Albion back to the bottom.
West Ham United made light of striker Craig Bellamy's absence, beating Fulham 3-1 to move further away from the danger area.
Wales international Bellamy, a reported target for Manchester City and Tottenham, was not included in the squad but his stand-in, Italian David di Michele, took his chance to impress in the lunchtime kickoff at Upton Park.
Di Michele put West Ham in front early on after a mistake from Fulham defender John Pantsil but Fulham levelled with an unstoppable shot from defender Paul Konchesky.
Mark Noble restored West Ham's lead from the penalty spot after halftime and Carlton Cole wrapped up the points to move West Ham into eighth place.
BOOED THROUGHOUT
Former West Ham boss Harry Redknapp, who left Portsmouth to become Tottenham manager in October, called for calm in the build-up to Sunday's clash after 11 Spurs fans were this week charged with indecent chanting at defender Sol Campbell during the reverse fixture earlier this season.
Campbell, one of several players on the pitch to have played for both clubs, was booed throughout by Spurs fans still bitter at his move to arch-rivals Arsenal in 2001 while Redknapp received some good-natured taunts from Portsmouth fans.
Redknapp, who had to re-shuffle his side during the game after injuries to striker Roman Pavlyuchenko and defender Ledley King, was facing a fourth consecutive home league game without a goal when Spurs trailed with 20 minutes remaining.
Nugent's strike, his first in the league for Portsmouth, looked like being enough to seal the points. However, Defoe made up for some earlier misses to bury a shot past England keeper David James after a lay-off from Luka Modric.
Darren Bent then wasted a glorious chance to win it for Spurs, heading wide from point blank range.
"You'll never get a better chance to win a football match," Redknapp told Sky Sports. "Jamo (David James) was ready to pick the ball out of the back of the net."
Redknapp confirmed that King had torn his hamstring and would be out for a lengthy spell.
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