Dan Housego scored 132 but still ended up on the losing side as South Africa beat Gloucestershire by three wickets in a 50-over tour match at Bristol.
Housego's 136-ball innings proved the mainstay of Gloucestershire's total of 261 after Proteas skipper Francois du Plessis had won the toss and put the home side in on a drying pitch.
But a largely second-string South Africa side were always in control of the chase and Wayne Parnell's hard-hitting 41 ushered the tourists to their target with six balls to spare.
In triumphal mood after winning the second Test at Lord's and displacing England at the top of the world rankings 48 hours earlier, South Africa sought to further stamp their authority ahead of the five-match one-day international series, which begins in Cardiff on Friday.
But the dress rehearsal did not go quite to plan as Housego, considered primarily a red-ball cricketer when he joined Gloucestershire from Middlesex last winter, set about reinventing himself in front of the County Ground's largest audience this year.
Far from helping the South Africans establish an important psychological advantage, this contest raised more questions than answers for the tourists as Housego offered England's batsmen much-needed encouragement.
Considered likely selections for the opening ODI at The Swalec Stadium, South Africa's spin triumvirate of Imran Tahir, Robin Peterson and Du Plessis all suffered at the hands of Housego and big-hitting James Fuller, who staged an explosive alliance of 94 in 12 overs for the seventh wicket as Gloucestershire recovered from 156-6 to post a competitive 261 in their 50 overs.
One of two members of South Africa's successful Test side on show at Nevil Road, Tahir's leg breaks went for 32 runs in five overs, while slow left armer Peterson conceded 48 from nine and Du Plessis 19 from two.
Seam bowlers Albie Morkel and Ryan McLaren took advantage of early moisture to undermine Gloucestershire's top-order and press their claims to face England in the opening ODI.
But any thoughts the tourists had of running through the home side and forcing an inside-the-distance victory were quickly forgotten once Housego and Fuller went to work.
If Fuller chanced his arm in typically cavalier fashion to harvest 39 at a run-a-ball, Housego played orthodox shots on his way to a 71-ball 50.
Accelerating smoothly thereafter, the 23-year-old former English schools 200m sprint champion, required just 48 balls more to move to his maiden one-day hundred.
In all, he faced 136 deliveries and accrued 11 fours and four sixes before aiming a tired drive at McLaren and losing his off stump in the 48th over.
Housego's electrifying innings contrasted starkly with that of England and Essex all-rounder Ravi Bopara, whose guest appearance for Gloucestershire was cut short when he slashed at a ball outside off stump from McLaren and was snaffled behind by Thami Tsolokile, having compiled three runs from 14 deliveries.
Proteas opener Hashim Amla had the look of a man who has spent a long time at the crease this summer as he gave South Africa's reply early impetus, raising 32 from 30 balls, including 5 fours and a six, before driving a short delivery from left-arm seamer David Payne straight to cover with the scoreboard on 39.
Dean Elgar and Justin Ontong maintained the tempo in a second-wicket stand of 69, but the introduction of Bopara and slow left armer Ed Young sparked a mini-collapse, the tourists slipping from 108-1 to 118-4.
Morkel and McLaren staged an alliance of 67 for the fifth wicket and South Africa required 77 from 13 overs when the latter holed out to deep midwicket for 38 to gift Fuller a wicket.
Parnell kept a cool head to guide the tourists to victory, compiling 41 from 31 balls and striking three fours and two sixes to finally break Gloucestershire resistance.