Man of the moment Michael Dunlop continued his Superbike dominance on the roads as the first day of practice got underway at the MCE Insurance Ulster Grand Prix.
The Hawk Racing BMW rider set the fastest lap of the day in the big class with a 121.602mph charge in the final session. Dunlop also topped the Superstock timesheets on a wet and miserable day at Dundrod.
Derek Sheils was next best with a speed of 120.913mph on the Cookstown Racing B.E. Suzuki, maintaining his impressive start after he earlier claimed pole for the Dundrod 150 Superbike race ahead of Honda Racing's Conor Cummins and Dunlop.
Jamie Coward, who has replaced the injury-hit Alan Bonner on the Devitt RC Express Kawasaki, was third fastest overall at 119.803mph followed by Dean Harrison (Silicone Engineering Kawasaki) and William Dunlop on the MMB Yamaha R1.
Peter Hickman on the GBmoto Kawasaki and Manx rider Dan Kneen (Mar-Train Yamaha) were the top eight.
Tyco BMW's Ian Hutchinson, who qualified eighth quickest for the Dundrod 150 Superbike race, opted to sit out the Ulster GP Superbike, Superstock and Supersport practice sessions.
Dunlop also led the earlier Supersport session on his MD Racing Yamaha, climbing to the top of the leaderboard with a lap of almost 118mph to head off Bruce Anstey on the Valvoline Padgetts Honda, with Derek McGee third fastest.
Southern Irish rider McGee led the way in the Supertwins class at 108.107mph on the Cookstown B.E. Racing Kawasaki from Dan Cooper and Michael Sweeney.
Joey Dunlop's son Gary, making his Dundrod debut, was eighth fastest in the Ultra-Lightweight session, which was headed by Christian Elkin.
Final practice takes place on Thursday along with the Dundrod 150 races. Roads close at 10am.