Michael Dunlop and Dean Harrison set the fastest speeds in the Supertwins and Supersport classes on the opening night of Isle of Man TT practice.
Dunlop, 29, set a new unofficial lap record of 120.875mph on his Paton, with Ivan Lintin second Twin at 120.660.
Harrison led the Supersports with a lap speed of 125.797 on the Silicone Engineering Kawasaki, followed by Honda-mounted Dunlop with 125.741.
Manxman Conor Cummins was third at 125.152 on his Padgett's Honda.
Saturday's first practice was led away by the solo newcomers to the Mountain Course - Adam Lyon, David Jackson and Davey Todd.
There was a delay of five minutes - to a scheduled start time of 18:20 BST - because of oil on the road between Cronk ny Mona and Signpost Corner.
When the action did get underway, the riders made the most of the perfect conditions, recording a series of fast laps, but it was Harrison and Dunlop who came out on top by the end of the session.
Fifteen-time TT winner Dunlop was inside James Hillier's Lightweight lap record on his second lap on the Paton, the Hampshire man's benchmark standing at 120.848 from 2015.
The Ballymoney man's effort does not erase Hillier's lap speed from the record books because it was set in practice rather than racing.
Practice will continue on Monday night, with the Superbikes, Superstocks and Supersports first out at 18:20 BST, followed by the Supersports and Lightweights at 19:25 and a first outing for the sidecars at 20:00.
Fastest Saturday practice times
|1. Dean Harrison (ENG)||Kawasaki||125.797mph|
|2. Michael Dunlop (NIR)||Honda||125.741|
|3. Conor Cummins (IOM)||Honda||125.152|
|4. Dan Kneen (IOM)||Honda||124.703|
|5. Peter Hickman (ENG)||Triumph||124.447|
|6. Lee Johnston (NIR)||Honda||123.245|
|1. Michael Dunlop (NIR)||Paton||120.875mph|
|2. Ivan Lintin (ENG)||Kawasaki||120.660|
|3. Derek McGee (ROI)||Kawasaki||117.571|
|4. Peter Hickman (ENG)||Kawasaki||117.508|
|5. Stefano Bonetti (ITA)||Paton||117.119|
|6. David Johnson (AUS)||Kawasaki||117.029|