After failing to take full advantage of their midweek match with Ilves, KuPS began their game with HJK determined to return to winning ways, and took the lead in the 17th minute when Otto Ruoppi curled the ball expertly into the top corner from over 20 yards.
But early in the second half, HJK won the ball inside the KuPS half, and Teemu Pukki laid it off at the edge of the box for Jere Kallinen to pick out the bottom corner with a sweet strike.
However, the Kuopio side were not behind for long - four minutes later, Piotr Parzyszek scored his sixth goal in as many matches in all competitions from the penalty spot, after a rash challenge from visiting goalkeeper Ricardo Friedrich on Bob Armah.
Then in the 90th minute, a fourth KuPS win in six Championship Group (CG) matches was sealed when Paulo Ricardo set up Agon Sadiku for the home side's third. The 3-1 loss leaves HJK still searching for a win in the CG from five attempts, and are now 10 points off the pace in fifth.
One point from their last three had put long-time leaders Inter Turku's title bid in real jeopardy, but they put that behind them and moved back into second with a 2-1 win over Ilves, who drop to third on goal difference.
It looked like more misery for FC Inter was on the way when Joona Veteli's penalty ensured the home side took the lead into half-time, but two Dimitri Legbo goals in the space of a minute late on turned the match - and the visitors' hopes - on its head.
The Turku side are four points off KuPS but with a game in hand. Ilves have also played an extra game, and now it's their challenge that looks to be fading, having taken just two points from their last four fixtures.
Still not out of the picture are SJK, who are six points off the pace, but also with a game in hand, having held on to beat Gnistan 4-3 away from home to record a third win in a row.
Rachide Gnanou not only cancelled out Kasper Paananen's opener, but put Gnistan 2-1 up early in the second half. However, the game swung on the hour mark - Paananen grabbed himself a brace a minute later, before Alenis Vargas and Valentin Gasc put the Seinajoki side 4-2 up with 14 minutes to play.
Saku Heiskanen pulled a goal back late on, but SJK saw out the victory that keeps them two points off European qualification. The loss for Gnistan confirms what has been known for a while - the Helsinki side will finish this season in sixth place.
Keep track of the title fight in the Veikkausliiga on Flashscore.