Alastair Cook gets back in the old routine before Critchley ton cements Essex advantage

Alastair Cook finally struck his 74th first-class century as Essex took advantage of perfect batting conditions in their LV=Insurance County Championship clash with Somerset.

England legend Cook had been dismissed for 99 for the first time in his career against Nottinghamshire, in his last innings before the start of the Vitality Blast. But he made no mistake by converting to three figures in 210 balls before reaching 128, as Essex racked up 360 for 4 on the opening day - with Matt Critchley providing entertainment in a sublime 119 during and after a 153-run stand with Cook.

On a grueling day for Somerset's bowlers, England quick Craig Overton was forced off the field in his 15th over after appearing to injure his left foot while bowling, although he did return and bowled a further three overs.

Tom Westley couldn't have been happier to win a toss with hot temperatures and a dry flat wicket on offer; batting was the only option, especially with the sweatless Cook ready to bed in.

Matt Henry and Overton found some early play and misses in a testing start to the day, which saw Nick Browne put down at second slip on 4. But things settled down and Browne and Cook put on their highest opening stand of the season - 66 - before the former tamely chipped to mid-off.

Somerset handed offspinner Shoaib Bashir a first-class debut, having recently made his T20 bow and received a two-year contract. The 19-year-old played age-group cricket for Surrey, Middlesex, and Berkshire before impressing Somerset while on trial last summer.

He started out his Championship career with a maiden to Cook, which included two deliveries that produced significant turn - sadly it wasn't a prophecy of things to come, although Cook would only score 20 runs off him all day. Bashir bowled 29 tidy overs from the River End, and despite going wicketless made scoring hard in his 0 for 89.

Westley is Division One's leading run scorer and took his season tally past 600 runs as he scored 37 in a 77-run partnership with Cook. He departed to a snorter from Overton which caught the outside edge through to the keeper. Paul Walter then put on 52 with Cook before he was bowled by Kasey Aldridge.

Throughout the day Cook was his classic self. Short on his pads, flicked off them. Short outside off, bat opened up and angled to ay gap. Overpitched, push through the covers. Anything that worried him, defended or left alone.

Fifty came and went in a workman-like 97 balls and only a drop at square leg when on 56 suggested he was fallible. He got stuck on 94 for 26 balls, and around an hour, either side of tea but reached three figures in 201 balls with a very fine clip to the boundary.

Cook is now tied with the likes of former Essex and Australia batter Ken McEwan and ex-Australia captain Greg Chappell on 74 centuries.

While Cook was regimented and steadfast, Critchley largely refused to budge from his aggressive style; if the ball was there to hit, he smashed it. The allrounder's fifth half-century of the season coming in 45 balls as he scored 78 of the first 100 runs of his fourth-wicket partnership with Cook.

Critchley had begun the season with three fifties but hadn't exceeded 20 in his last five innings, on this occasion he converted his second ton - in 116 balls - for Essex since arriving at the beginning of last season.

Cook fell lbw to Josh Davey with five overs left in the day to give the visitors some rare cheer at the Cloud County Ground, Chelmsford.