Mike Yardy is to quit his Sussex coaching job to join New South Wales as batting coach.
The 38-year-old former England World Twenty20 winner will leave his position at the end of July to join the Australian state side.
"I'm excited about the chance to work with New South Wales," said ex-Sussex captain Yardy, who took up his coaching role at Hove in 2017.
"It was an opportunity I couldn't afford to let pass by."
Yardy, who was Sussex skipper from 2009 to 2012, combined his coaching role with that of second XI/batting coach at the start of last season, and also worked as an England Young Lions batting coach.
Sussex director of cricket Keith Greenfield said: "Yards has been a hugely important and committed part of Sussex's journey for the best part of three decades in his roles as player, captain and latterly as coach.
"We wish him well with his new opportunity in Australia as he strives to become the best coach possible and, one day, a head coach. We're delighted to have helped him on his way to those goals."
Yardy's years with Sussex
Yardy's association with Sussex began at under-10 level, running until his retirement as a player at the end of the 2015 season.
In 187 first-class matches for the county, he made 10,693 runs, as well as hitting 3,226 runs and taking 114 wickets in 170 List A matches.
He is also still the county's fifth highest run-scorer (1,030) and second highest wicket-taker (77) in T20 cricket.
Apart from winning the 2010 ICC World T20 with England, he also played 28 one-day internationals, before his exit from international cricket in 2011.
Yardy helped Sussex win the County Championship three times - in 2003, 2006 and 2007 - as well as the C&G Trophy in 2006 and the Pro40 League in 2008 and 2009, the same year they won the Twenty20 Cup.
Sussex, who appointed former Australia Test bowler Jason Gillespie as head coach in November 2017, are third in Division Two in the County Championship.
After reaching last year's final at Edgbaston, Sussex start their new T20 Blast campaign against Hampshire at the Rose Bowl on 19 July.