Filan made his first Premiership appearance of the season in Wigan Athletic's 1-0 win at Everton.
And the Australian repaid his manager's faith by producing a fine save from James McFadden to deny the Toffees a late equaliser.
Jewell was still wrestling with his conscience after the Goodison Park victory which lifted Latics up to eighth in the table.
He said: "It was a tough decision to leave Mike Pollitt out, one of the hardest I've ever had to make because he has been fantastic for us.
"I just felt it was the right time to bring John back in, obviously Polly wasn't best pleased and I understand that.
"What was difficult was that Polly hadn't done anything wrong and I'd told him previously that if he played well, he would stay in the side.
"I went against that, I don't know why, I just had a gut feeling it was the right thing to do.
"John has been fantastic for us, so has Polly, and I've got two great keepers in competition for the shirt.
"I think John will realise now he has to play very well to stay in the side."
Latics' win over Everton, courtesy of Damien Francis' first goal for the club, meant they have taken 10 points from the last 12 on offer.
And with the Carling Cup win over Bournemouth also thrown in, Latics are unbeaten in five games.
It's a run Jewell is pleased with, although he had to dish out a stern half-time lecture to his troops to get the desired result on Saturday.
He said: "In the first half, I was a bit of a madman and couldn't wait to get the lads into the dressing room.
"It was the old game of two halves, and I thought we were rubbish in the first half to be perfectly honest.
"We didn't show anything we had been working on in training during the week, Everton were first to every ball, but the second half was a role-reversal.
"We got the early goal, grew in confidence from there, and we had the better chances after that.
"This is a tough league we're playing in against some quality sides. Okay, Everton are struggling at the minute but we still had to go there and match them on the pitch.
"We're now on 10 points, but there's still an awful lot of hard work to do yet.
"I think we can do better and we'll be working in training to try to do that.
"But we'll enjoy this victory, it was a derby game against Everton who are a great club, and it was lovely to see so many of our supporters cheering us on through the game"
Jewell was pleased to see Francis get off the mark, his goal coming less than a minute into the second half.
"You have seen what a fantastic team talk can do," he joked.
"It was a good move leading up the goal, a good save from their keeper, and there was Damien following up.
"I was pleased for him and the team when it went in.
"When we scored the goal, there must have been four or five of our players in the box, which was good.
"One of the reasons we bought Damien was for him to make those runs and get into the box, although he was still doing them with five minutes to go which was something I didn't buy him to do."
Latics have landed a home tie against Watford in the third round of the Carling Cup, with the game likely to be played on October 25.
And the Australian repaid his manager's faith by producing a fine save from James McFadden to deny the Toffees a late equaliser.
Jewell was still wrestling with his conscience after the Goodison Park victory which lifted Latics up to eighth in the table.
He said: "It was a tough decision to leave Mike Pollitt out, one of the hardest I've ever had to make because he has been fantastic for us.
"I just felt it was the right time to bring John back in, obviously Polly wasn't best pleased and I understand that.
"What was difficult was that Polly hadn't done anything wrong and I'd told him previously that if he played well, he would stay in the side.
"I went against that, I don't know why, I just had a gut feeling it was the right thing to do.
"John has been fantastic for us, so has Polly, and I've got two great keepers in competition for the shirt.
"I think John will realise now he has to play very well to stay in the side."
Latics' win over Everton, courtesy of Damien Francis' first goal for the club, meant they have taken 10 points from the last 12 on offer.
And with the Carling Cup win over Bournemouth also thrown in, Latics are unbeaten in five games.
It's a run Jewell is pleased with, although he had to dish out a stern half-time lecture to his troops to get the desired result on Saturday.
He said: "In the first half, I was a bit of a madman and couldn't wait to get the lads into the dressing room.
"It was the old game of two halves, and I thought we were rubbish in the first half to be perfectly honest.
"We didn't show anything we had been working on in training during the week, Everton were first to every ball, but the second half was a role-reversal.
"We got the early goal, grew in confidence from there, and we had the better chances after that.
"This is a tough league we're playing in against some quality sides. Okay, Everton are struggling at the minute but we still had to go there and match them on the pitch.
"We're now on 10 points, but there's still an awful lot of hard work to do yet.
"I think we can do better and we'll be working in training to try to do that.
"But we'll enjoy this victory, it was a derby game against Everton who are a great club, and it was lovely to see so many of our supporters cheering us on through the game"
Jewell was pleased to see Francis get off the mark, his goal coming less than a minute into the second half.
"You have seen what a fantastic team talk can do," he joked.
"It was a good move leading up the goal, a good save from their keeper, and there was Damien following up.
"I was pleased for him and the team when it went in.
"When we scored the goal, there must have been four or five of our players in the box, which was good.
"One of the reasons we bought Damien was for him to make those runs and get into the box, although he was still doing them with five minutes to go which was something I didn't buy him to do."
Latics have landed a home tie against Watford in the third round of the Carling Cup, with the game likely to be played on October 25.