"You have a choice." It's a mantra that has served Tammy Beaumont well this year and the benefits were there for all to see again as she guided England to an emphatic eight-wicket victory in the first of three ODIs against India in Bristol.

Beaumont scored 87 runs off as many balls, having shared an unbroken partnership worth 119 for the third wicket with Nat Sciver, whose run-a-ball 74 was as brutal as Beaumont's was clinical.

It was the fourth consecutive ODI innings in which Beaumont had passed fifty after scores of 71, 72 not out and 88 not out on England's winter tour of New Zealand and followed her 66 in England's only innings of the drawn Test between these two sides at the same ground just over a week ago.

Beaumont has also scored two centuries in her past 10 ODI innings, against Pakistan in December 2019 and during the Ashes series the previous English summer, but she said her work with Phoebe Sanders, the team's sports psychologist, earlier this year proved a turning point.

"The day before the first game in New Zealand she said to me, 'you know you have a choice how you go about it'," Beaumont said on Sunday. "Ever since then her voice has been in my head as I'm walking out, 'you know you have a choice how you approach it, you can kind of go with the flow and see what happens or you can go out and try to dominate and try to be relentless'.

"And it's not about dominating like how other people might do it, my dominating is making sure that I put away every bad ball I get and make them really work hard to get me out and it seems to be working so hopefully it'll continue."

There was a period during her latest innings when it seemed like Beaumont only dealt in fours.

She survived almost being run out on nought when she set off for a run after being struck on the pad and Ekta Bisht's throw to the non-striker's end from cover point was wayward, then an India review when she was given not out lbw on the same ball - the DRS showing Shikha Pandey's in-ducker was sliding down the leg side.

After Lauren Winfield-Hill's campaign to cement a place as opener ahead of next year's World Cup was off to a fleeting but entertaining start when Jhulan Goswami had her edging behind, Beaumont seemed to continually find the boundary.

She struck back-to-back fours off Pandey, through point and driven in front of square, and then off Pooja Vastrakar with a wonderful straight hit back over bowler's head followed by a precision cut through point as she and Heather Knight took 13 off the over.

Beaumont then hit twin sweeps to the boundary off Bisht so that at the end of the first Powerplay, England were 61 for 1 compared to India's 27 for 2. By the time Beaumont had racked up 39 runs off 30 deliveries, she had eight fours to her name.

Even with spin stemming the flow of runs somewhat, and Bisht ending a 59-run partnership with Knight with a beautiful delivery that took the top of off stump, Beaumont's strokeplay was all class. She brought up a 48-ball fifty with a four swept off Deepti Sharma and struck Vastrakar to the point boundary with perfect poise and timing.

"The main thing is I've stopped believing in form," Beaumont said. "Once you get to a certain age you've worked on your technique, you know what works and it's just a case of sticking to it and doing the tinkering with it if something's going wrong.

"But if it's going right then for me it's all about your mindset... that's what I've really been working on, being ruthless and relentless as much as possible and it seems to be working at the moment."

Sciver settled in with a couple of fours off Bisht before being dropped on 12, off Harmanpreet Kaur, and beaten four times in succession by Pandey.

Appointed permanent vice-captain ahead of this multi-format series after standing in for the injured Anja Shrubsole on the tour of New Zealand, Sciver scored a valuable 42 in the Test and the runs came in abundance on Sunday as she punished bad balls and good in powerful fashion.

With the rain that had been threatening to arrive all day starting to fall in a sparse drizzle, Sciver struck the tenth four of her innings off Kaur followed two balls later with a thumping six down the ground as it looked like she might overtake Beaumont.

"Once Nat starts to unleash there's no stopping her and at one point I thought I wasn't going to get to face another ball," Beaumont said. "But she was very kind to me in the end. For me, today was all about getting the job done and being not out at the end. If I tried to keep up with Nat there's no chance, she's just an unbelievable talent."

After pulling Goswami for four, the petite Beaumont, who stands about a foot shorter than Sciver, weighed in with a six of her own, launching Kaur over long-on to level the scores. Kaur's next ball was a wide to seal the result in something of an anti-climax, given the batting display by England to that point.

The margin of defeat was also something of a let-down for India, who had lost a thrilling World Cup final by just nine runs the last time these two sides met in an ODI on English soil, in 2017. And as preparations for the next World Cup begin in earnest, this match gave both teams plenty to ponder.

Valkerie Baynes is a general editor at ESPNcricinfo