Smriti Mandhana struck a match-winning 91 to guide India to a comfortable seven-wicket win over England in the first one-day international at Hove.
Captain Harmanpreet Kaur finished 74 not out to take India to their target of 228 with 34 balls to spare.
Kate Cross claimed 2-43, but England’s young bowlers struggled, with Yastika Bhatia hitting 50 for India. England earlier slipped to 94-5 before Alice Davidson-Richards’ unbeaten 50 helped them post 227-7.
India, who were inconsistent in the Twenty20 series that England won 2-1, put in an assured all-round performance and capitalised on their hosts’ inexperience.
Veteran seamer Jhulan Goswami conceded 20 runs and took one wicket from her 10 overs, while Deepti Sharma claimed 2-33.
With England needing their remaining senior players to step up in the absence of injured captain Heather Knight and Nat Sciver, batter Danni Wyatt added a fluent 43. Still, stand-in skipper Amy Jones and opener Tammy Beaumont made just 10 runs between them.
In reply, India lost Shafali Verma early, but Mandhana and Bhatia, who survived two dropped chances, added 96 for the second wicket before Harmanpreet calmly kept her side on track and finished the match with a six to take the tourists to 232-3.
The series continues with the second ODI at Canterbury on Wednesday.
Mandhana leads the way for composed India
England’s inexperience was perhaps even more glaring with the ball.
Without the rested Katherine Brunt and Sciver, who is taking a break to focus on her mental health, England’s seamers struggled for the same nagging consistency that Goswami managed.
Cross led the attack well but lacked support as Issy Wong, and Davidson-Richards sent down too many loose deliveries for Mandhana and Harmanpreet to punish.
The hosts struggled in the field, too. Bhatia was dropped by Wong and Jones, while Wong also put down Harleen Deol on nought.
England’s spinners Ecclestone and Dean were economical but unthreatening, as Mandhana played a chanceless, classy inning until she skied a delivery from Cross to Davidson-Richards.
Jones’ inexperience as captain was apparent – England had no answers for Mandhana’s effortless scoring all around the ground or Harmanpreet’s composure.