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Having topped the running on Wednesday with a time of 1m40.793s on the new Kawasaki ZX-10RR, Rea lowered the benchmark by half a second to end the two-day test 0.179s clear of his 2020 title rival Scott Redding.
It was Garrett Gerloff who held the top spot for much of the second day of testing despite a crash in the morning at Turn 7, his early flyer of 1m40.790s remaining unbeaten
until the final hour.
Rea was the first to usurp the GRT Yamaha rider from the top spot, finding nearly three tenths on his previous best time of 1m40.802s to return to the front of the order.
The American managed to strike back with half an hour remaining in the session, his time of 1m40.497s enough to usurp Rea's 1m40.519s benchmark.
However, a series of improvements from rivals in the final 10 minutes shook up the order at the front of the field, with Rea eventually ending quickest of all his with his last-gasp effort of 1m40.264s.
Ducati man Redding also managed to dislodge Gerloff in the dying minutes of the session, ending up second and 0.054s clear of the GRT rider.
Jonas Folger made a late improvement on the satellite MGM Racing BMW to end up fourth with a time of 1m40.699s, ahead of the second Ducati of Michael Ruben Rinaldi and the factory BMW of 2013 champion Tom Sykes.
Alex Lowes, who has now fully recovered from a shoulder injury he picked up earlier in the year, made a considerable improvement from the opening day of running, ending 0.931s off the pace of his Kawasaki teammate Rea in seventh.
Factory Yamaha rookie Andrea Locatelli was an impressive eighth, while the top 10 was rounded off by Chaz Davies on the Go Eleven Ducati and the top Honda of Leon Haslam.
Haslam's teammate Alvaro Bautista completed just six laps in the morning after admitting that he was not feeling 100 percent following a recent motocross crash, ending up 18th out of 20 riders in the timesheets.
Toprak Razgatlioglu was forced to withdraw from the test following a positive COVID-19 test after only nine laps of running, his best lap placing him 15th.
|5||21||Michael Ruben Rinaldi||Ducati||78||1:40.756||+0.492|
|14||60||Michael van der Mark||BMW||62||1:41.945||+1.681|
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