The Australian got the nod to return to the north coast road race eight years after his last appearance at the event after Michael Dunlop split from Paul Bird’s team last month.
Dunlop had done a deal to ride the Ducati Panigale at the NW200 and Isle of Man TT but shelved those plans, after expressing dissatisfaction with the commitment from Paul Bird’s BSB team.
Dunlop has reunited with the Hawk Racing team to ride a Suzuki and made an impressive start on Tuesday, ending the session second in the times, only 0.173s behind Brookes.
The Ballymoney man lapped at 119.967mph, with Brookes breaking the 120mph barrier with a lap of 120.045mph.
Davey Todd impressed on the Milenco by Padgett’s Honda, with the English rider only 0.891s down on Brookes, while Alastair Seeley was also in the mix on the IFS Yamaha R1 following a lap of 119.64mph.
The top four were covered by nine tenths of a second, with Glenn Irwin – winner of the last four Superbike races at the North West – two 2.1s off Brookes’ time in fifth on the Honda Racing UK Fireblade.
Last year’s man of the meeting James Hillier with sixth on the OMG Yamaha followed by 2019 top newcomer Richard Cooper (Buildbase Suzuki) and Manx rider Conor Cummins (Milenco by Padgett’s Honda).
FHO Racing’s Peter Hickman was 10th behind 14-time winner Michael Rutter (Bathams BMW) after only managing three laps, with John McGuinness 12th fastest for Honda Racing UK.
The full session was held in dry and sunny conditions around the 8.9-mile course just before a huge downpour in Portrush.
1 J Brookes (Ducati) 120.045mph
2 M Dunlop (Suzuki) 119.967mph +0.173s
3 D Todd (Honda) 119.648mph +0.891s
4 A Seeley (Yamaha) 119.64mph +0.909s
5 G Irwin (Honda) 119.095mph +2.145s
6 J Hillier (Yamaha) 118.801mph +2.815s