Sunderland are now the closest to Pompey in the League One title race.
The Black Cats have climbed above Peterborough into second spot and are three points behind the Blues with a game in hand.
While Jackett’s men won 1-0 at Bradford, Sunderland earned a 2-0 win at struggling Plymouth.
The team managed by Jack Ross now have five wins in a row.
Aiden McGeady put Sunderland in front with a great individual goal after beating a couple of defenders and curling in from 20 yards in the 53rd minute.
McGeady doubled his and the Black Cats' tally with a penalty 12 minutes from time to extend their unbeaten league run to eight matches.
Wycombe ended Peterborough's unbeaten away record in League One with a 1-0 success at Adams Park.
Bryn Morris' deflected free-kick from 20 yards proved to be the difference as the Chairboys made it four straight home wins.
The Posh have slipped to third are now five points back from leaders Pompey.
Burton grabbed only their second away win of the League One season so far as they cruised to a 3-1 win at Walsall.
Northern Ireland international Liam Boyce missed a penalty for Burton before Jamie Allen fired them into a 13th-minute lead with a deflected strike.
Devante Cole slid in to double Albion's advantage before the break, and they made it 3-0 through Scott Fraser shortly after the restart.
Andy Cook grabbed a late consolation for Walsall.
AFC Wimbledon suffered their seventh straight league defeat as they fell to a late 2-1 reverse at home to Shrewsbury.
James Hanson put the home side ahead 10 minutes before half-time with a fine header but a Luke Waterfall double earned the visitors their first away win of the season.
Oxford scored their 3,000th Football League goal but they let a three-goal lead slip in a 3-3 draw at Scunthorpe.
The visitors took an eighth-minute lead through James Henry after he latched onto a Jamie Mackie through ball to smash home.
Cameron Brannagan grabbed the landmark goal before Curtis Nelson put Oxford into a 3-0 lead after 55 minutes.
But three goals in an eight-minute spell from Jordan Clarke, George Thomas and Charlie Goode hauled Scunthorpe back for a share of the spoils.
Gillingham inflicted Joey Barton's heaviest league defeat as a manager when they ran out 3-0 winners against Fleetwood.
Brandon Hanlon opened the scoring after 11 minutes before a Tom Eaves brace either side of half time earned back-to-back victories for Gillingham for just the second time this season.
Ollie Clarke scored a brace and Tony Craig's volley condemned Blackpool to their second home loss of the season in a 3-0 defeat to Bristol Rovers.
A late Kieffer Moore goal earned Barnsley a 1-0 triumph against Southend to stay in fourth.
Charlton saw off Doncaster with a 2-0 win thanks to goals from Joe Aribo and Karlan Ahearne-Grant.
Sixth-placed Accrington ended seventh-placed Coventry's five-match winning run with a 1-1 draw, while Luton remain in fifth despite playing the final 16 minutes with 10 men after Danny Hylton was sent off in the goalless draw at Rochdale.