Modric has been out for two months with a fractured fibula, suffered in the win over Birmingham, and Spurs staff are cautious about setting a date for the Croatia playmaker to return to action.
Lennon, 24, is still considered a long-term absentee and will certainly be out for longer than Lennon, who has been earmarked for a return from his ankle injury after the international break, making him a doubt for England's friendly against Brazil in Qatar.
Striker Jermain Defoe is available after for the Sunderland clash this weekend after serving a three-match suspension but centre-back Sebastien Bassong will miss out with a hamstring problem.
Jonathan Woodgate could deputise after returning from a head injury suffered against Stoke.
He (Woodgate) has been pretty unlucky against Stoke to take a bang, said Tottenhamassistant boss Joe Jordan.
He'll be back in contention.
Spurs boss Redknapp feels his team have suffered without the attacking influence of Modric, Lennon and Defoe.
They are three of my best players, he said. Modric is a world-class player in my opinion. Lennon is a threat when he has the ball and goes at people.
Defoe has been in incredible form this year. Suddenly we miss him for three games. It's cost us dearly when he got sent off at Portsmouth.
Meanwhile, Spurs have announced an initial two-year official club partnership with Hong Kong club South China.
The relationship with the Hong Kong-based football club will look to focus on football and commercial development, read a statement from Spurs. This will include a best practice exchange programme, a shared knowledge of coaching methods and techniques, as well as coach visits.