The hosts grabbed the lead in the opening 45 minutes, and continued to dominate after the break to cruise to a deserved victory
Hyun-Jun Suk gifted the hosts the lead in the first half with a good finish from a narrow angle, before Leandro Bacuna made it two after the break. PSV were then dealt another blow as Stanislav Manolev was dismissed after receiving his second booking. Again Suk put the match to bed halfway through the second half with a brilliant long range strike.
The guests started the match with attacking intentions and came close to opening the scoring early on. Nevertheless, Tim Matavz's header after a cross from the right went just over the bar.
Groningen then took over the initiative and deservedly went ahead in the 29th minute. Suk cut inside from the right to play a quick one-two with Petter Andersson, before finding the net with a low shot from a narrow angle.
PSV almost restored parity shortly after via Dries Mertens, as the winger went past his direct opponent and unleashed a powerful shot in the near corner. However, Groningen goalkeeper Luciano showed his class with an excellent save to deny the Belgium international.
The home side doubled their lead in the second half after a superb counterattack. Dusan Tadic got the ball down the left after good work from David Texeira, and set up Bacuna with an intelligent pass through the middle. The youngster did not hesitate and found the net with a placed shot from the edge of the area.
The table-toppers were then reduced to ten men as Manolev received his second booking of the afternoon after being adjudged of diving inside the Groningen box.
Tadic missed a big chance to make it three for the Green-White Army around the hour-mark, but his powerful shot was saved by Andreas Isaksson. Nevertheless, Groningen did make it three in the 74th minute after some sloppy defending from PSV. Isaksson failed to properly clear a weak Zakaria Labyad back-pass, and Suk reacted alert before lobbing the goalkeeper from 45 yards out.
PSV still sit atop of the table with 45 points from 22 games, but they will drop to second position if AZ do not lose their game later on Sunday. The Eindhoven giants resume match action on Thursday when they host Trabzonspor in the Europa League.
Groningen climb to eighth spot in the table following this weekend's result with 32 points. Their next Eredivisie match is the away game against NEC on February 26.