St Johnstone’s fourth Tayside derby win of the season edged Dundee closer to the Premiership precipice.
Saints full-back Scott Tanser and centre-forward Callum Hendry put the ineffectual visitors to the sword and completed a campaign whitewash over their troubled neighbours.
Jim McIntyre’s Dundee are six points adrift of second-bottom St Mirren and have just four games left to engineer an escape from the automatic relegation spot, having now lost an unprecedented eight top-flight matches in a row.
Tommy Wright’s seventh-placed Saints should have won even more comfortably.
Three minutes later Kennedy made space for a teasing cross but Hendry’s six-yard diving header flashed narrowly wide.
The same combination almost unlocked the Dundee defence in the 18th minute. This time Hendry’s troublesome header was pushed out low at the post by alert goalkeeper Dieng.
The lethargic visitors finally got an effort on target in the 28th minute but Ryan McGowan’s header from Nathan Ralph’s free-kick was easily held by St Johnstone goalkeeper Zander Clark.
Dundee centre-back Darren O’Dea was booked for tripping Hendry in the 53rd minute. There was further punishment to be meted out as left-back Tanser stepped up to sweep home the 25-yard free-kick despite Dieng getting a hand to it en route to the top corner.
It came minutes after Dundee substitute Andrew Nelson had tugged a rare chance wide. Man of the match Kennedy almost got on the scoresheet but Dieng was able to divert the winger’s goal-bound shot.
