Essex 182 and 45 for 2 trail Derbyshire 323 (Durston 116, Poynton 50*, Madsen 50) by 95 runs

In mechanics, momentum is the product of mass and velocity. In sport its impact is massive though difficult to measure but the product of Tom Poynton's weight of runs - 50 - by their velocity - 35 balls - produced momentum that put Derbyshire on the victory path for the fourth time this season.

Poynton's innings, his first-class best, came against the tide. Derbyshire had lost 4 for 28 and sacrificed a position from where they might have hoped to bat once. Their lead was 96, still significant, but Essex's fightback and knowledge of a good surface was enough to have the hosts believing there was a way back into the match. Cue Poynton. Then two wickets in nine balls at the start of Essex's second innings: Alviro Petersen playing a horrible shot away from his body trying to drive a full ball and Tom Westley pushing at another swinging ball for Tim Groenewald's second wicket. Funny thing momentum.

Poynton would not have expected to play too great a part in Derbyshire's season, with captain Luke Sutton taking the gloves but his sudden retirement saw Derbyshire coach Karl Krikken turn to Poynton. He has been protected, coming in at No. 9, enabling him to focus solely on his glovework. But teams no long carry wicketkeepers so it will have been a relief to Poynton to have finally made a meaningful score after a previous best this season of 15.

Always batting with the tail, he might have some licence to play strokes but his dismissals this season have been playing rather tentatively. Here he unleashed seven fours and two sixes - the latter clearing the pavilion with a slog-swept full toss - and made his maiden first-class half-century. The 10th wicket stand with Groenewald added 45 at almost eight-an-over. A stand which made Derbyshire feel a whole lot better and gave them a third batting point.

They did not need rescuing but they should have made more of their opportunity to kill the game. At 161 for 2 shortly after lunch a lead of 200 was well within them. But there were too many giveaways. Dan Redfern played across the line to edge Charl Willoughby to James Foster; Ross Whiteley holed out to mid-on off Tom Westley; Martin Guptill had earlier pulled a ball to the same field placing.

They were also hindered by a decision against Wayne Madsen. He was adamant he did not touch a ball from David Masters to Foster, said the replays backed him up and he always walks. Madsen and Wes Durston looked to be set to bat all afternoon after putting on a comfortable 77. But Derbyshire failed to build another stand and lost momentum. Thus Wes Durston's stay proved not the highest score of many but the essential knock.

Durston scored at a good lick too, taking 49 balls for his half-century and 110 balls for his second century in three matches. "It's exactly how I wanted to bat when I went in," Durston said. "I was slow to 20 but then it clicked. It's not the fastest wicket and spun more as the day's gone on."

Durston played the legspin of Tom Craddock, who took a maiden five-wicket haul in first-class cricket, with confidence. Durston is in good form. He used his feet well and swept well. It was his fifth hundred since joining Derbyshire in 2010 and like David Wainwright, who was unsuccessful in five overs before the close, he has been given a new lease of life after being released from the county he began at. Durston spent eight years at Somerset but found a path back through the Unicorns.

"I've pretty much played every game in two years since I've joined and that's exactly what I needed," Durston said. "I never doubted my own ability just needed the chance to play. I don't think I've done a huge amount to my game." He's perhaps regaining momentum in his career.