Michael Dunlop was quickest on the BMW Superbike at the first practice session for the Southern 100 at Billown on Monday evening.
He put in a lap at 112.355mph to head Dean Harrison and Champion Guy Martin.
On his return after several years absence, Dave Molynuex with passenger Benjamin Binns were fastest and only 2.6 seconds away from the lap record at 98.120mph.
Dean Harrison tops the 600cc class at 107.298mph ahead of Guy Martin and Dan Kneen.
He's also quickest of the 650cc Supertwins at 99.936mph to lead James Cowton and brother Adrian.
And Alistair Haworth is fastest in the 400cc at 94.844mph.
Tom Snow was the quickest 250 and 125 during the evening.
The second practice session is this evening with roads closing at 6.05pm to reopen no later than 9.40pm.
The first two races also take place - at 8.05pm there is the Corlett's Trophies 600/1000cc Race followed at 8.45pm by the Station Garage 125/400/450cc Race.