With the Latics manager believing the top two are almost out of sight, he is now targeting the play-offs as a route to the Premiership.
Latics had taken a 73rd minute lead last night, Andy Liddell putting away his ninth goal of the season from the penalty spot.
But the game swung the way of the hosts within two minutes when John Filan tripped Lee Hughes in the box, giving away a penalty and earning himself a red card.
Hughes beat substitute keeper Gary Walsh from the spot and then set up Thomas Gaardsoe's 91st minute winner.
Filan will get a one-match ban for his dismissal – there will be no appeal – sitting out the home clash with Second Division bound Wimbledon on April 3.
The defeat was cruel on Latics who have now picked up just one point from the last nine on offer.
And Jewell knows vital ground has been lost on the top two who are pulling away from the rest of the chasing pack.
He said: "I think Norwich and West Brom are getting away and it will be difficult for them to be caught.
"Things can change quickly at this stage, just ask Wolves about what happened to them a couple of years ago.
"I'm sure, though, that Gary Megson and Nigel Worthington won't allow their players to take their foot off the gas.
"Looking at ourselves, for us to be in the top six at the moment is great.
"We are not making any rash predictions one way or the other, and our aim is to try and keep doing better.
"If we give everything we have got in the next 10 games, let's see where it takes us."
Despite the defeat, Jewell praised his players last night, and he hopes the squad will take positives from the performance into Saturday's home game against Coventry.
He said: "I thought we deserved at least a point for our endeavour.
"We matched West Brom for workrate and physical presence, and in the second half, we got the ball down and passed it better.
"It was a tight game as we expected, and it was just disappointing to concede the goals we did.
"We let them back into it with a poor goal, but I'm not saying it wasn't a penalty.
"I've no complaints with it, although I don't know whether the referee should have sent John off – a penalty might have been enough of a punishment.
"But it came from a long ball up the field which we didn't react quickly enough to.
"After that, we would have taken a creditable point, and it was all hands to the pump with a man down.
"I couldn't have asked for any more from the players in effort as we held West Brom comfortably until the end. I thought we were better than them, and made them change their system.
"For the home team, they didn't really have too many chances."
Goalscorer Liddell echoed the thoughts of his manager, describing the defeat as a "sickener". He said: "It was cruel wasn't it?
"Everything happened so fast at the end.
"We were 1-0 up and then suddenly we were down to 10 men and they had a penalty.
"It was sickening, an absolute sickener when they scored the winner.
"West Brom are going to go up, make no mistake about that, but I didn't feel they were the better team, we were at least on a par with them.
"But at the end we weren't marking and we paid a big price for that."
Source: Wigan Evening Post.