Redknapp said earlier this month that he was loath to play Modric as his "head's not in the right place", but he was named in the starting line-up for Sunday's 5-1 defeat to Manchester City.
Modric, though, has made clear on more than one occasion that he remains determined to sign for Chelsea, and reports in the press on Sunday morning claimed the Blues are preparing a £40 million bid to prise the midfielder away from White Hart Lane before Wednesday's deadline.
Redknapp said after the defeat: "Luka came to me at 11.30 this morning and said to me, 'I don't feel my head is right today'. I said, 'I feel you need to play today, Luka. I need you to play. You need to come and play'.
"I told him we had injuries and I said, 'I need you to come and play. We need you on the pitch, get out and play'. I told him he was our main man.
"I'm sure he is getting advised to maybe not play today. We have seen it with other clubs. He was okay yesterday morning to play and obviously something happened last night. Who knows what went on?
"Some of the papers today were saying that they are ready to make a £40 million offer. While he still sees a chink of light to go to Chelsea, he is probably doing what maybe people are telling him the best way of getting out of here is."
Despite Modric's determination to move on, Redknapp remains confident the midfielder will be staying put.
"There has been a feeling around the place that the place hasn't been right since the start of pre-season," Redknapp added. "It has been a bit of a difficult period really.
"When people want to go it can be a problem but hopefully in another day or two when the window closes he will still be here and we'll all move on. I don't think he's going to go. The chairman said he isn't. When he comes back from international duty the window will be closed."
Redknapp also revealed that, having just signed Emmanuel Adebayor and Yago Falque on loan, he is confident of adding further players to the squad.
"I still think we will be there. We will get one or two in the window," Redknapp said. "We are hoping to sign another player today. I wouldn't want to say who but we are looking to make another signing.
"I have said to the chairman that the place needs a little lift now. I feel I have got everything I can out of them now."
West Ham midfielder Scott Parker is thought to be on the verge of a move, while Craig Bellamy and Lassana Diarra are also options. Redknapp said: "I like Bellamy. He's a possibility. I like Diarra."