Gnistan have already proven they can upset the big boys this season, and they looked like causing another shock when a complete miscontrol from goalkeeper Aatu Hakala allowed Joakim Latonen to steal in and put them 1-0 up after 16 minutes.
But the visitors were rocked by three KuPS goals in the final eight minutes of the half, which began with Agon Sadiku applying a close-range finish, before Joslyn Luyeye-Lutumba bundled the ball home from a corner - his fourth goal in two matches.
Before the break, Sadiku added his second when a blocked shot fell kindly for him inside the area, and he made no mistake with the finish.
Hakala made another mistake early in the second half, spilling a long-range effort from Didrik Hafstad, but Gnistan weren't back in it for long - three minutes later KuPS were awarded a penalty, and Sadiku stepped up to complete his hattrick.
Petteri Pennanen drilled a low strike from 25 yards in for number five, then 10 minutes from time, Mohamed Toure raced away from a tired Gnistan defence to make the final score 6-2.
It's a second league win in a row for the champions after their poor run, while Gnistan have won once in their last six.
That took KuPS top of the table for what was expected to be a 24-hour stint, however, they will remain at the summit for a while longer as Inter Turku were held to a goalless draw at home to Mariehamn.
The league's unbeaten side had a golden opportunity to secure three points with 20 minutes to go, but Axel Kouame failed to convert from the penalty spot.
It's three draws in their last four now for the stalemate specialists, while the positive point cannot prevent Mariehamn dropping a place to ninth.
The Turku side have dropped to third after Ilves held off a late fightback from strugglers KTP and seal a 2-1 home victory to keep them a point behind KuPS.
Oiva Jukkola grabbed the opener just inside the quarter-hour mark for the Lynx, who doubled their advantage in the opening seconds of the second half, courtesy of Marius Soderback.
Substitute Rangel pulled a goal back five minutes from time, but KTP were unable to find a dramatic equaliser and stay one point clear of last-placed AC Oulu, who did not play this midweek.
The shock of the round went to Jaro, who stunned HJK by coming from 2-0 down to secure a 3-2 triumph in Helsinki to move themselves within four points of the top half, as HJK stay fifth after successive losses.
Usual suspects Alexander Ring and Teemu Pukki did the damage for HJK either side of half-time, both scoring their seventh goals of the season, with Ring scoring a tremendous free-kick.
But then it was the turn of Jaro's and the league's top goalscorer to shine - Kerfala Cissoko scored his eighth and ninth of the season in a five-minute spell to get the visitors back on level terms.
Then, six minutes into stoppage time, the Bolt Arena crowd were silenced when Rudi Vikstrom popped up with the winner for Jaro, who have now won two of their last three, as HJK lose twice in under a week.
Finally on Wednesday, Haka came from a goal down to beat VPS 2-1 away from home to move eighth, two places and three points behind their opponents, who are winless in three matches.
Maissa Fall put the hosts in front early on, before an Eetu Mommo thunderbolt and a Jean-Pierre Da Sylva winner had turned things around by the 33rd minute.
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