Dunlop is the winner ahead of Hickman and Harrison. Jamie Coward was fourth ahead of Davey Todd.
Hickman pips Harrison to P3 thanks to a stunning final lap.
Harrison is across the line but Dunlop wins the first race of the week.
Just one second separates Harrison and Hickman heading over the mountain section. There's not long left int he first race of the 2023 Isle of Man TT.
Harrison has extended his lead over Hickman for P2 at the start of lap four and he's currently quicker than Dunlop, who is choosing to back off rather than go for the lap record.
Dunlop is still leading by a comfortable margin of 17 seconds, while Hickman is catching Harrison for second.
If Dunlop is to set a lap record it will come on the final lap, although it would be a big ask for the current leader.
Dunlop leads by over 16 seconds heading through the mountain section on lap three.
+12.189s is the deficit Harrison is facing at the moment as Dunlop is controlling things out front.
Dunlop's lead is still growing and he's now 13+ seconds clear of Harrison. Hickman is still in P3.
The first stops are now taking shape at the end of lap two. Leader on the road, Harrison is in pit lane
Still on lap two, Dunlop is now 11 seconds clear of Harrison and remains on lap record pace.
Dunlap is a whole two seconds inside the Supersport lap record as his lead goes over 10 seconds.
Dunlap is continuing his ominous charge and could break the lap record at some stage. It won't be on lap two though as riders will need to slow down for the lone pit stop .
Dunlop takes another second out of Harrison coming across the start-finish straight. The Yamaha rider leads by -5.488s.
Dunlop's lead is currently -4.493s over Harrison - Hickman is still third.
Dunlop insreases his lead by a further second as riders hit the mountain section.
Dunlop increases his lead from one second to three seconds over Harrison.
Dunlop is the new leader after finding time on Harrison.
Harrison is fastest from Dunlop and Peter Hickman through the first split.
Dean Harrison is flying on this opening lap.
And we're underway! David Johnson is the first rider to set off.
We're just moments away from the race getting underway and riders tackling Bray Hill.