|Specsavers County Championship Division Two, Chelmsford|
|Essex v Gloucestershire (close, day two)|
|Gloucestershire 262: Roderick 88no; Porter 4-59|
|Essex 287-6: Westley 121, Cook 105; Taylor 2-12|
|Essex 5 pts, Gloucestershire 4 pts|
England Test captain Alastair Cook made a century for Essex at Chelmsford against Gloucestershire in his first County Championship innings of 2016.
The 31-year-old opener reached his 52nd first-class hundred off 182 balls.
Cook shared a second-wicket stand of 222 with Tom Westley, who was caught behind for 121, before being trapped lbw by off-spinner Jack Taylor for 105.
Josh Shaw took his first Championship wickets, removing Dan Lawrence and Ryan ten Doeschate as Essex closed on 287-6.
England's first Test match of the summer is against Sri Lanka at Headingley, starting on 19 May.
And Cook, England's leading run-scorer in Test cricket, requires just 36 more to become the first England player to reach the milestone of 10,000 Test runs.
He is one of several England players appearing for their county during the opening rounds of Championship fixtures.
Essex stuttered following the dismissal of the two centurions. Liam Norwell bowled Ravi Borapa cheaply before Shaw had Lawrence caught at mid-off attempting a pull, and then trapped Ten Doeschate lbw in consecutive overs.
Rain brought play to an early close, with the home side holding a slender first-innings lead of just 25 runs despite the batting masterclass from Cook and Westley.
England captain Alastair Cook told BBC Radio Essex:
"It was nice to get a few and it has helped put us in a good position, although it was disappointing that we lost four wickets towards the end and let Gloucestershire back into the game.
"I've been happy with the way I've been playing pre-season, so it was nice to get a hundred. If you put the ball in the right areas, there's a bit of help for the bowlers but, if you don't, then you get punished.
"But it's a good cricket wicket. The conditions changed with the new ball because it became overcast and then started to rain. But that's the beauty of four-day cricket. Conditions can change."