Skinner fastest as Mackenzie suffers new injury blow, round one in doubt?

Skinner, who was already quickest during session #2, kept hold of his place atop the leaderboard thanks to a time of 53.730s. 

The Kawasaki rider made a good start to pre-season testing at Snetterton last month - part of a six-rider group that went underneath the existing lap record - before continuing to demonstrate serious potential ahead of his second season in BSB. 

• Official: Tarran Mackenzie to make WorldSBK debut at Assen 
• Bradley Ray shows impressive pace on Yamaha debut, a sign of things to come? 
• Rea unleashes devastating pace to top final pre-season WorldSBK test at Aragon

"We have had a mega day and to be straight back on the pace was good," said Skinner. "Conditions have been a bit varied today, there was rain in the afternoon and the wind has also been high all day, so that has made pushing on a bit difficult, but we were able to string together some longer runs.

"Towards the end we put together a couple of fast laps and I am really happy with how the day went and the team have been really great. 

"FS-3 Racing have given me a great bike for the test and I am looking forward to tomorrow."

Also making a great start was Bradley Ray aboard his Rich Energy OMG Racing Yamaha machine. 

Ray, who will be riding an R1 for the first time in his British Superbike career this season, was less than a tenth off Skinner. 

But while the pace was frantic - top 22 riders were separated by less than a second - the big news from the final test before next week’s season-opener, again at Silverstone, was the accident involving Mackenzie. 

The reigning champion already suffered a fractured right tibia and dislocated right shoulder during a fall at Cartagena in January, but following a nasty highside as he came onto the old start-finish straight, the McAMS Yamaha rider has a suspected left ankle fracture. 

Will Mackenzie miss round one? 

Although it remains to be seen what the extent of his injury is, an already less than 100% fit Mackenzie is now at risk of missing round one. 

Worryingly for Mackenzie, this month’s BSB round might not be the only event he could miss, as the Scottish rider is also scheduled to make his WorldSBK debut in the form of a wildcard at round two in Assen (April 22-24).

Mackenzie has previously shown a remarkable ability to fight through injuries, which suggests anything is possible.

Medical update: Following assessment at University Hospital Coventry, Tarran Mackenzie has been diagnosed with a fracture to the left ankle. He will see a specialist in Nottingham tomorrow (Friday) for further consultation.