A century from either side saw Glamorgan's trip to Canterbury end up in a draw with Kent in their Division Two clash.
The hosts posted 168-2 in their second innings on a pedestrian final afternoon in Canterbury as former England Under-19 batsman Northeast carried his excellent limited-overs form of late into the four-day game by stroking 11 fours.
The 22-year-old was making the most of ideal conditions in a rain-ruined match at the St Lawrence Ground as promotion-chasing Kent banked 11 points to Glamorgan's 9.
The outcome of the game, though, rested on the first session of day four when Glamorgan resumed on 264-7 and needing a further 43 to avoid the follow-on.
Kent seamer Charlie Shreck accounted for John Glover leg before in the early exchanges but the turning point came in Shreck's next over when Wallace, on 49, nicked one behind only to see Kent keeper Geraint Jones down a tough diving chance in front of first slip.
Wallace went on to post a 192-ball century and feature in a ninth-wicket stand with Dean Cosker worth 103 in 19 overs that denied Kent their chance to enforce the follow-on.
Glamorgan's batsmen battled towards saving the follow on against Kent after they made it to 264-7 after a delayed start to day three at Canterbury.
Kent declared on their overnight first-innings total of 456-9 when play finally started at noon, setting the Welsh county 307 to avoid the follow-on, and by stumps the visitors were only 43 short of their target with three first-innings wickets intact.
When Matt Coles bagged two early wickets to help reduce the visitors to 83-4 all appeared to be going Kent's way until former Surrey captain Stewart Walters and then Glamorgan vice-captain Jim Allenby dug in to frustrate the hosts for much of the afternoon.
Walters combined with Allenby to add 84 in 19.3 overs for the fifth wicket, before Allenby took on the anchor role as he and wicketkeeper Mark Wallace (46 not out) combined to add a further 87 in 31.4 overs in the best batting conditions of the game.
Allenby, having battled for three hours, was only 14 short of his century when he tossed away his own wicket against the occasion left-arm wrist-spin of Brendan Nash.
Kent will look to claim Glamorgan's three remaining first-innings wickets quickly on the final day and will be favourites to force a victory should they do so.
Glamorgan hit back on a rain-hit second day of their Division Two clash with Kent to restrict the hosts to 459-9 at Canterbury.
Kent were 310-4 overnight with two unbeaten centurions - Brendan Nash and Darren Stevens - at the crease.
But the visiting bowlers ensured they would not be facing a 600-plus total in the final two days, though Geraint Jones hit a fine 69 not out before the rain arrived at 2.20pm to force an eventual abandonment.
Nash and Stevens fell within the space of 12 deliveries; Huw Waters having the former caught behind for 114, then Stevens (123) chipped a checked drive to extra cover.
James Tredwell (11) nicked to slip off James Allenby, who then moved to slip himself to catch Matt Coles who hit a breezy 26 before falling to Dean Cosker.
Mark Davies also chipped in to the home cause with a bright 24 before James Harris - who took all four wickets to fall on Thursday - whistled one through his defence.
Jones made the most of some rare support from Kent's rabbit at No 11, Charlie Shreck, who hit his first ever first-class six in his 120th innings.
He hung around for half an hour for his seven not out as Jones completed a 74-ball half century.
Brendan Nash and Darren Stevens both hit centuries to help Kent dominate the opening day of their Division Two clash with Glamorgan at Canterbury.
The duo came together with their side in trouble but shared an unbroken stand that was worth exactly 200 to carry their team to 310-4 by the close.
England Lions bowler James Harris, whose season has been disrupted by injury, took all four wickets to fall on Thursday, but the support from the rest of the Glamorgan attack was poor.
The seamer had Rob Key (14) and Ben Harmison (12) caught behind by wicketkeeper Mark Wallace and was on a hat-trick after dismissing Sam Northeast (52) and former Glamorgan batsman Mike Powell for a first-ball duck.
But from then on West Indies international Nash and experienced all-rounder Stevens built a superb partnership to swing the momentum Kent's way.
Left-hander Nash (110no) was first to get to three figures and he was soon followed by Stevens, who ended the day unbeaten on 120 having hit 21 boundaries.