AB de Villiers produced a batting masterclass to guide Middlesex to a seven-wicket win over Essex at Lord's on the opening night of the T20 Blast.
The South African, making his first appearance in English domestic cricket, scored 88 not out off 43 balls.
Elsewhere, England World Cup winner Moeen Ali took 4-18 as holders Worcestershire beat Notts Outlaws.
In Thursday's other match, Tom Banton hit 64 off 34 balls in Somerset's eight-wicket victory against Glamorgan.
Colin Ingram plundered 26 off Glamorgan's final over to leave the visitors 181 to win at Sophia Gardens, but a rapid opening stand of 98 between Banton and Pakistan's Babar Azam set up the One-Day Cup winners' successful run chase.
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An A* display from AB
De Villiers, one of the most destructive limited-overs batsmen of his generation, is the marquee new arrival in this summer's competition and he did not disappoint in front of a sell-out crowd at Lord's.
The 35-year-old was part of a moment of magic in the field, relaying a catch on the boundary to George Scott which removed Dan Lawrence.
Essex went on to post 164-6 in their 20 overs, Ryan ten Doeschate top-scoring with 74 not out.
Middlesex slipped to 39-2 in reply and De Villiers started patiently alongside England's Dawid Malan, but the pair soon picked up the pace and went on to share a 105-run third-wicket stand.
De Villiers, who struck five fours and six sixes, is available for Middlesex's first seven group fixtures and could return for the knockout stage if his side qualifies.
Holders make winning start
Moeen, who captained Worcestershire to a maiden T20 title in 2018, was the first of England's world champions to return to county action.
He made 32 with the bat, but it was Ed Barnard's 42 not out off 19 balls late in the innings which got the visitors up to a decent total of 161-6 on a slow pitch.
Notts opener Alex Hales, who was not considered for England's World Cup squad after serving a 21-day ban for reportedly failing a drugs test, gave his side a positive start with a 32-ball half-century.
However, once he departed for 52, bowled by a Barnard slower ball, the hosts' challenge subsided.
Moeen ended with four wickets and, aided by some impressive fielding, Worcestershire eased to victory.
"Ed has had a good night," said Moeen. "He's a great all-rounder, and bats, bowls and fields brilliantly.
"We have made a very good start, having done so well last year. We've got a lot of belief in our side and a lot of confidence. We try to do the right things as much as we can."
England one-day captain Eoin Morgan paraded the World Cup during the innings break at Lord's, four days on from a gripping final victory over New Zealand at the same venue.
He doesn't seem to be too bored of carrying that thing around.
There are seven matches on Friday, with three more of England's World Cup winners expected to play a part for their counties.
Hampshire duo James Vince and Liam Dawson have been made available for their side's home fixture against Sussex, while Tom Curran could be in action for Surrey against Essex at Chelmsford.
Fresh from their victory on the opening night, Worcestershire will face neighbours Birmingham Bears at New Road.