But Jewell revealed today his early release had already been agreed if the Scots had nothing more to play for.
He said: "There's nothing seriously wrong with his knee – just slight medial damage.
"He is okay to play. But I spoke to Walter before Saturday's game and, if there was no chance of them qualifying, he was always going to let him come back anyway.
"He played on Saturday without an injection. He just has a little bit of pain.
"Actually he got a bang on the toe, but he will be fine for Saturday."
McCulloch has needed pain-killing jabs before each of his five Premiership games for Latics this season.
But he refused medication on Saturday and managed to get through the full 90 minutes against Belarus.
The Scot returned home yesterday while his international team-mates flew out for their meaningless match in Celje.
Jewell, who expected McCulloch to report for training today, added: "He isn't 100 per cent fit, but he is getting better all the time.
"At the moment he can't play three games in a week – Saturday, Wednesday, Saturday. So that is the reason he is missing the trip to Slovenia.
"But he managed to play on Saturday without an injection and that was the first game he has played this year without one. So obviously he has got over that hurdle now.
"I don't want to stop him playing for his country. But it was agreed he would not go to Slovenia if Scotland could no longer qualify."
McCulloch was one of seven Wigan players away on international duty over the weekend.
There were no reports of any injuries to the other six, but Jewell still faces an anxious wait with four of them – Irish duo Graham Kavanagh and David Connolly and England Under-21 pair Leighton Baines and Ryan Taylor – still involved in midweek.
Kavanagh and Connolly are on duty in Dublin against Switzerland tomorrow while Jewell travels to Hillsborough tonight to watch Baines and Taylor against Poland.
Henri Camara has returned from Dakar where he netted twice for Senegal in the 3-0 win over Mali at the weekend.
Josip Skoko is also back in Wigan after playing most of the second half of Australia's 5-0 thrashing of Jamaica in London on Sunday.
Jewell will not have his complete squad together until Friday morning, just 24 hours before Michael Owen, Alan Shearer and Co arrive at the JJB for the televised game with Latics (12.45pm kick-off).
He said: "That's the worst problem (about international duty) – not having your players to prepare with.
"It looks like being Friday before I have them all back and that isn't ideal. But Newcastle have the same problem too.
"It is part and parcel of having international players.
"We are grateful for the break as the Premiership is so intense. But it was still strange having a weekend off."
A strong Latics Reserves side won 2-1 at West Brom last night in the Premiership Reserve League (North), with all the goals coming in the second half.
Youngster Sam Litchfield gave Latics a 47th-minute lead.
A bizarre Mike Pollitt own goal saw West Brom level on 65 minutes, but Andreas Johansson headed in the winner five minutes later. Also in the Latics side were David Wright, Matt Jackson, Emerson Thome, Steve McMillan, Gary Teale and Alan Mahon.