Barnsley made four changes from the side which lost 1-0 at Wycombe last Saturday with Dimitri Cavare, Adam Jackson, Brad Potts and Daniel Pinillos coming back in.
Portsmouth named an unchanged side despite a 2-1 home defeat to Charlton in midweek.
The Reds went into the game having been knocked out of the top six by Doncaster's derby win over Scunthorpe in the early kick-off.
There was a high tempo opening despite the freezing rain and Barnsley went the closest when Kieffer Moore headed Adam Davies's long ball into the path of Cauley Woodrow, who immediately let fly a right-footer which Craig MacGillvray could only parry away into the path of Brad Potts, who volleyed over.
MacGillvray came to the rescue again, pushing over another first-timer from Woodrow following Moore's low cross from the right to the edge of the area.
It was George Moncur's turn to test the Pompey goalkeeper next, accepting a return pass from a short corner and firing the ball towards the near post only to see it pushed out for another flag kick.
MacGillvray tipped over Cameron McGeehan's long-range drive for Barnsley's fifth corner of the half before Ronan Curtis saw his shot blocked for Pompey's first, which Oliver Hawkins headed off target.
Jamal Lowe also volleyed wide from Lee Brown's deep cross for the visitors.
Barnsley got back on top and Moore screwed an attempt wide before a blunder by Alex Mowatt handed Pompey the lead in the 43rd minute.
Mowatt retrieved a wayward Pompey pass on the goal line but only cleared to the edge of the Barnsley area where unmarked Evans fired home inside Davies's left-hand post.
It left the Reds with an uphill task as they attacked the Pompey end in the second half when Jacob Brown replaced Cavare.
Potts fired narrowly over as the icy rain continued unabated.
A patient build-up paid dividends in the 62nd minute when Potts, out on the right, knocked the ball towards the near post and Woodrow slid in to knock the ball home.
Lloyd Isgrove replaced Moncur as the reds fans found their voice.
Davies made a smart stop down to his right to deny Hawkins from the edge of the area as Pompey continued to threaten on the break. They lost dangerman Ronan Curtis to injury, however, and Anton Walkes took his place.
The Reds made their final change in the 80th minute when Mamadou Thiam replaced Potts.
Moore had a great chance to win it in the 90th minute but hit wide with a shot on the turn after being set up by Isgrove.
Neither side could conjure a chance in the four minutes of stoppage time.