Keith Andrews buried the Blues' second-half winner as they edged a scruffy contest at Portman Road to move into the top six.
The victory was their fourth in a row on home soil and extended their unbeaten run to six games.
However, Ipswich were far from their best and Jewell joked: "I should be wearing a mask.
"Last year we murdered them and lost 2-0. Tonight, we were basically hopeless.
"But I said to the lads at half-time that if you want to be successful in football, you've got to get something from games when you don't play well.
"Portsmouth were the better side but we kept working, rode our luck and desire got us through.
"It would have been a decent result for us if we'd drawn 0-0.
"Portsmouth are a big side and they caused us problems all over the pitch.
"We started all right but then looked a bit edgy.
"Sometimes as a manager, results like that are as satisfying as when you play really well, though.
"It gives us confidence that when we're not at our best we can get dig in, get our blocks in and win ugly.
"But it wasn't a vintage performance by any stretch of the imagination."
Town's winner came just after the midway point in the second half.
Carlos Edwards swung in a cross from the right, Nathan Ellington headed it down and Andrews steered home his fifth goal in a Blues shirt.
By that stage, the goal was coming and it seemed likely there might be more.
However, Town had to be content with one - something they will have no complaints about after a less than convincing first half.
Unchanged for the sixth match in a row, they lived dangerously and were fortunate to be level at the break.
Pompey had some glorious chances - not least when former Town skipper David Norris put Luke Varney clear, but the striker's low shot was saved by David Stockdale.
Dave Kitson scuffed a close-range effort wide and then Ricardo Rocha and Joel Ward should have done better with headers gathered by Stockdale.
Varney had another gilt-edged chance straight after the restart, yet failed to make contact in front of goal, before Edwards stirred the restless home fans with an angled shot which flashed wide of the Pompey post.
Portsmouth caretaker-boss Guy Whittingham is still adamant he does not want to become the permanent successor to Steve Cotterill.
He explained: "Nothing's changed in that respect. After the game on Saturday I had a headache until ten o'clock.
"Then I couldn't get off to sleep. When I did get to sleep I woke up at four o'clock and I couldn't get back to sleep again.
"I don't want that every week - but I would like to stay on in my capacity as a coach.
"We're hoping to give the club enough time to get the right person in.
"We're enjoying it and the players are enjoying it, but if we find out someone is coming in before the weekend then so be it."
Whittingham was delighted with his side's performance.
The former Pompey striker added: "That's the best 90 minutes we've played all season.
"We knew it was going to be tough but our lads were determined and had a game plan.
"It worked well, apart from scoring goals.
"We were very pleased and in a few days' time we'll reflect on what a good performance it was.
"At the moment, though, we're just totally disappointed that we lost the game."