Twente triumph in table-topping clash
Twente lead with 63 points and five matches remaining, two ahead of PSV.
PSV had the better of the first half but failed to score and Twente took control midway through the second period when Bryan Ruiz came on and was fouled in the area shortly afterwards.
Janssen converted the penalty and settled the match eight minutes from time when he finished off a 60-metre run with a brilliant lob over goalkeeper Andreas Isaksson.
AZ Alkmaar remain fourth with 52 points following a 1-0 win at 10-man Feyenoord. Charlison Benschop struck on the stroke of half-time before Gill Swerts was sent off just before the hour.
Roda JC Kerkrade stayed on track for a Europa League play-off berth by winning 5-4 at bottom side Willem II Tilburg.
Lowly Excelsior Rotterdam got their first away win of the season after recovering from 2-0 down to win 3-2 at Heerenveen, with Geert Arend Roorda, on loan from Heerenveen, scoring twice.