Keaton Jennings celebrated his England call-up with an unbeaten hundred as the Lions beat the UAE by eight wickets, in Dubai.
The Durham opener led from the front as captain by striking 101 not out off 105 balls as his side eased to 175-2 off 33.1 overs in replay to the UAE's 174 all out.
The uncapped 24-year-old, called into the England squad on Wednesday as a replacement for injured Haseeb Hameed, timed his century perfectly one week ahead of the fourth Test against India.
Jennings shared a century opening stand with Daniel Bell-Drummond, who contributed 40 before falling with the score on 103 from 21.4 overs.
Tom Alsop (24) fell with the Lions needing just nine more runs to win the first of three 50-over contests.
Earlier, the hosts struggled after Middlesex seamer Toby Roland-Jones removed Laxman Sreekumar for one before the Surrey trio of Tom Curran (2-26), Sam Curran (2-25) and Stuart Meaker (4-38) rattled through the order.
Meaker made the key breakthrough, ending a 54-run stand for the second wicket by removing opener Rohan Mustafa (33) before Ollie Raynor (1-44) bowled number three Ghulam Shabeer (33).
"That couldn't have gone much better," Jennings said after the match. "It was our first game together in the field after six or seven weeks, and a really enjoyable experience for me captaining the team.
"To spend some time in the middle for me was great, even if they were one-day runs - which is obviously different to how things will be in India."
Watch live coverage of the fourth Test between India and England live on Sky Sports 2 from 3.30am on Thursday December 8.