Dimitri Cavare’s strike and an own-goal from Will Wood gave Barnsley victory over Accrington.
With Pompey losing to Charlton and Sunderland drawing at Wycombe it has given the Reds some breathing space in second position.
They also cut the gap on leaders Luton, who drew with Plymouth, to three points.
But the title is not something Barnsley head coach Daniel Stendel is dreaming about yet.
The next big challenge for him is the huge clash at home with Sunderland on Tuesday, while Pompey will be at Walsall and Luton go to Bradford.
Barnsley’s manager enjoyed the other results on Saturday. He told the Yorkshire Post: ‘The first goal is to get automatic promotion. We have no chance to influence what Luton do but it is exciting.
‘When we saw results from other stadiums it made it a good win. We cannot influence other results so you can only say it’s good for us when we win our games.
‘We controlled most of the game but it was not our best performance although we deserved to win. I am very proud. Jordan Green had his first game in the starting 11 and he had a good start. It’s good to see other players coming in and doing well. It’s a good experience for us.’
Given they have now gone 16 matches unbeaten Barnsley will be confident they can beat Jack Ross’ team on Tuesday.
If they do they will open up a cushion of seven points over Sunderland in third.
Stendel added: ‘We will now enjoy it on Tuesday. It is a big game and we are looking forward to it. I think we can win this game and we will be very happy if we do.’
Fourth-placed Pompey are now eight points back from Barnsley and have a two-point advantage over fifth-placed Charlton with Doncaster a further eight points back in sixth position.