Alex Lowes finished the first of two days testing at Jerez fastest from WorldSBK rookies Iker Lecuona and Xavi Vierge. 

Lowes, who was last of the four WorldSBK riders that completed laps to venture out, was third at the midday stage as Vierge led by less than a tenth from Lecuona. 

Vierge's time of 1:41.248s was ultimately lowered to a 1:41.316s by Lowes, however, Vierge also dropped his lap time to the tune of nine tenths which was good enough to put the Team HRC rider just +0.024s behind Lowes come the end of play. 

"We didn’t make too many laps but we have a really good schedule of things to test so we need to make sure that if we choose something new, it’s definitely better," Lowes told the official World Superbike website after topping day-one. 

"It’s easy to make the wrong decision. We tried a couple of things today; I have a couple more things to try tomorrow. Between here and the Portimao test, hopefully we can finalise our base bike for 2022. 

"I tried some new parts from Showa on the front of the bike, we tried some electronic parts that were positive. Tomorrow, we’re going to focus more on the rear of the bike to try to have some confidence in the middle of the corner, to lift the bike, and get off the corner a little bit better. 

"Today was more focused on the front, and tomorrow we’re going to look a bit more at the rear. If we get through another two or three items tomorrow, it’s been a good test for us."

Lecuona was the first rider to head out as he returned from a left finger injury suffered during last December's Jerez test. 

Like his team-mate Vierge, Lecuona worked extensively on the electronics and traction control of his CBR1000RR-R - improved grip, turning and handling being the primary focus within that. The former MotoGP rider finished third a tenth-and-a-half shy of Vierge. 

The final WorldSBK rider in action was Puccetti Kawasaki's Lucas Mahais who made his on-track return for the first time in four months. The second-year rider was fourth quickest. 

In regards to day-two, it remains unclear if six-time WorldSBK champion Rea will complete a full or half day. The 34 year-old, who yesterday won the Irish Motorcyclist of the Year award for a record-breaking ninth time decided to skip today's action in order to save one of the ten test days that each rider is allowed. 

Heading a seven-rider strong WorldSSP field was Turkish rider Can Oncu, while mentor and former five-time Supersport champion Kenan Sofuoglu made his return aboard an MV Agusta F3 800 machine. 

Sofuoglu was replacing the MV Agusta Reparto Corse team's new addition for 2022 Bahattin Sofuoglu after the ex-WorldSSP300 rider tested positive for COVID-19.