The ECB's player replacement trial rule has been used for the first time in County Championship history, as Essex captain Tom Westley was replaced after breaking his finger in their opening match of the season against Hampshire.
Westley was forced to retire hurt on 28 after being struck on the glove by a ball from England's Sonny Baker, and his side applied to use an injury replacement after Essex's medical team ruled him out of the rest of the match.
Umpire Steve Davis then approved Essex's proposed change, allowing all-rounder Noah Thain to replace the No 5 in the batting order, meaning Essex will be able to use 12 different batters in their first innings.
Thain, though, will be forbidden from bowling, having replaced a specialist batter in the line-up.
The ECB's new rule is part of a wider ICC trial on player replacement, and includes an eight-day cooling-off period for any replaced player - meaning Westley is likely miss Essex's next Championship fixture at home to Somerset.
Trials are already under way in first-class tournaments in India, South Africa and Australia, and it has already been the subject of controversy down under after Victoria's Sam Elliot was replaced by Mitchell Perry on day three of the Sheffield Shield final.
