Bruce Anstey lit up practice at the Classic TT with a brilliant lap in excess of 118mph on the Padgetts Honda RS250, fractionally short of John McGuinness's 1999 lap record.
The 11-time TT winner, who won the last 250 TT on the Mountain Course in 2002, threw down the gauntlet ahead of Saturday's Sure Lightweight TT race with a lap of 118.24mph, which compares to McGuinness's benchmark of 118.29mph.
Michael Dunlop on the Team Classic Suzuki XR69 set the first 125mph lap of the meeting (125.562mph) in the later Superbike session. The Northern Ireland rider eclipsed Dean Harrison's lap set 10 minutes earlier on the Silicone Engineering Kawasaki (124.823mph) to confirm his status as the favourite for Monday's Motorsport Merchandise Superbike Classic TT race.
John McGuinness was experiencing the ups and downs of racing on the TT Mountain course, sliding off the Team Winfield Paton at Quarterbridge on his opening lap of the session before returning to the Grandstand and posting the fastest time of the week to date in the class at 110.363mph on his second lap.
In Saturday's Bennetts Senior Classic TT race, the Morecambe man will be hoping to end a run of misfortune, having failed to finish in the three previous 500cc Classic TT races.
In the Lightweight class, Anstey's time dominated the session and established him as the clear favourite with his time almost 40 seconds ahead of Ian Lougher's lap on the Laylaw Yamaha from Tuesday's session.
In the Superbike session, Dunlop and Harrison dominated with their fastest laps of the week but Austrian Horst Saiger on the Greenall Racing Kawasaki posted his fastest lap of the week at 123.049mph to finish the week third fastest overall.
Dunlop's time of 102.567mph on the Black Eagle Racing MV Agusta was the fastest Junior time of the week but brother William also signalled his intent with another lap of 100mph on the Davies Motorsport Honda.