Jason Roy 81, Chris Jordan four-for seal spoils for Surrey in London Derby

Jason Roy and Chris Jordan provided the stamp of authority with bat and ball as Surrey dominated the London Derby at Lord's. After overcoming a spirited challenge in the powerplay from Middlesex's captain, Stephen Eskinazi, they surged to a 20-run victory that extends their unbeaten run at the top of the South Group, and reaffirms the strong sense that this could yet be their year, 20 seasons on from their maiden such title in the Twenty20 Cup's inaugural season.

It's not often that Surrey's cast of Galacticos has tripped over its own feet in this most imposing of campaigns, but that was arguably the case in a curiously incomplete display that probably could have been a 230-plus total, maybe should have been nearer 180 had it not been for a controversial reprieve for Jamie Overton, and instead finished on a merely imposing 208 for 7.

For that total, Surrey were indebted to another big-dog display from Roy, a man who heads off for England duty in the Netherlands on Sunday with a bristling tally of 131 from his last 86 balls of Blast duty. His share here was 81 from 45, a performance that began with a volley of six fours and two sixes in the space of his first 17 - one of them as effortless as flicking a bogey over the short Grandstand boundary, as Surrey romped to 50 for 0 in a frantic first four overs.

Thereafter, however, their innings didn't develop with the aplomb that they might have envisaged. Will Jacks, the main man in Wednesday's demolition of Sussex, got bored with being second fiddle and hoicked a steepling leading edge to mid-off off Jason Behrendorff, before Sam Curran - Hampshire's destroyer at The Oval last week - was undone by a Test-match beauty from Toby Roland-Jones, an off-stump lifter that seamed and kissed the edge through to John Simpson for a third-ball duck.

Just five runs had been added in 14 balls either side of those wickets before Roy got proper hold of the strike once more, whereupon he rushed through to his 25-ball fifty with a four and six in consecutive balls off the spinner Chris Green. But Martin Andersson's pace-off slowed the tempo in a six-run over before he struck brilliantly in his next, a bewildering reaction catch as he clung on to a full-blooded mow from Laurie Evans, head-high to his left.

Excellent though his introduction had been, Andersson's efforts took a dent during a lively 25 off 15 balls from Sunil Narine, including a flat six over the head of the boundary rider and a streaky inside-edge for four.

Narine seemed surer in his shot selection against Green, as he twice reversed his stance to sweep through the vacant third man. Green, however, lured a loose drive to cover in the same over, before Andersson - returning for his fourth over - seemed to have claimed the double strike that could give Middlesex a fighting chance.

On 81, and seeking a bout of raw acceleration, Roy under-edged a hard back-foot slash into his own stumps, and tossed his bat in frustration at letting a clear-cut century chance slip, before Overton - on 0 from 3 at the time - appeared to be a second victim of Andersson's outstanding reactions, as he flung himself full-length in his followthrough with his outstretched left hand.

The luxury of the Sky cameras meant the umpires were able to send the decision upstairs - with a soft signal of "out" for good measure - but after a lengthy deliberation, the verdict "Not out" was flashed up on the big screen to widespread bemusement, presumably due to the bowler not being in full control of his movements as he tumbled to the pitch with ball in hand. Either way, it was a critical let-off, and Overton took full toll, clattering three fours and two sixes from his final seven balls, before Jordan hoisted the total past 200 in a 15-run final over from Tom Helm.

The sense that Surrey had left a few runs unaccounted for was soon put into violent context by Eskinazi and Max Holden, who came tumbling down the pavilion steps, ready for a brawl. Seventy-six runs and no wickets spilled out of the powerplay, with Eskinazi tearing lumps out of Dan Worrall's first over in particular, with a six into the Grandstand hospitality boxes and a helicopter four over third man to complete a 19-run over.

Holden, initially left standing by his captain, picked up the pace with gusto, lacing three fours in a row in Curran's second over. But just when the chase was threatening to get out of hand, up popped Surrey's captain Jordan. Holden holed out to square leg off his very first ball - the first after the powerplay - before Narine bamboozled Eskinazi for 47 with a skiddy wicket-to-wicket delivery that flicked his off bail and required a third-umpire's review to convince the batter that he hadn't been stuffed by the keeper.

Narine had no such recourse in the same over when Eoin Morgan, batting for only the second time this season, appeared to be nailed incredibly adjacent to the stumps. But it would be a very temporary reprieve. An unconvincing innings of 5 from 10 balls ensued before Overton tempted him with a hoick to deep midwicket, where Curran was waiting to pocket the chance.

At 92 for 3 in the tenth over, the innings was now at its make-or-break moment … and it duly broke, a collapse of 3 for 3 in six balls effectively ending any remaining jeopardy. John Simpson scuffed a pull to midwicket off Narine, before Jordan popped up with two more in two, Joe Cracknell to a good stooping catch from Curran at long-on and Andersson bowled through his legs for a first-baller, to complete a performance of rich promise on a duff note. Despite Green's belated belligerence, it transpired that being adequately imposing was quite imposing enough for the Blast's high-fliers.