NATWEST T20 Blast champions Birmingham Bears are guaranteed a quarter-final place in this year's competition after beating closest rivals Worcestershire Rapids by five wickets in front of a sell-out crowd at New Road.

The North Group leaders opened up a four-point gap as old-hand Rikki Clarke kept his cool in making an unbeaten 52 from 43 balls as the Bears made it five wins in a row.

Tom Kohler-Cadmore and Brett D'Oliveira made half-centuries in taking the Rapids to 160 for five and the Bears overcome a chaotic start to complete a successful run-chase with three balls to spare after a quick-fire 22 not out by Ateeq Javid.

It was an earlier partnership of 68 in nine overs by Clarke and Laurie Evans (35) which restored order before the latter was caught at long-on off Saeed Ajmal.

In the closing stages, wicketkeeper Ben Cox intermittently employed the tactic of discarding his gloves and taking up a sort of long stop position, but it made no odds as the Rapids suffered a blow in their bid for a quarter-final spot.

Their innings had been a tale of two exciting academy-developed prospects and two contrasting phases.

Kohler-Cadmore registered his third half-century in the competition and D'Olviera, from the third generation of a famous cricketing family, reached an explosive 50 from 29 balls, his highest score in all formats for the first-team.

Yet for all this enterprise, the Rapids were tied down for more than half of the innings as Warwickshire's three spinners conceded only 70 runs - and three boundaries, all by Kohler-Cadmore - in the space of 11 overs.

On a sluggish surface, which was used for two previous T20 games, Worcestershire were only able to break out of the shackles when D'Oliveira hit four sixes as pace bowlers Oliver Hannon-Dalby and Recordo Gordon were carted for 56 off the last four overs.

When D'Oliveira hoisted the last ball of the innings over long off, the 23-year-old all-rounder was undefeated with 56 from 30 deliveries, having more than doubled his previous best in the competition.

Worcestershire had made the worst possible start when captain Daryl Mitchell came down from a midweek double-century in the County Championship to a first-ball duck when he steered rather than smashed a short ball from Clarke to backward point.

Richard Oliver was bowled for 10, aiming to slog wrist spinner Josh Poysden's opening delivery, and Colin Munro was smartly stumped by Tim Ambrose off Jeetan Patel.

Kohler-Cadmore managed to shut out problems at the opposite end by taking five boundaries in the power play and the former Malvern College batsman was up to 66 from 51 balls when he holed out to deep mid-wicket off Poysden (two for 20).

In contrast Warwickshire's top order lurched into trouble. Brendon McCullum hit two sixes but the New Zealand captain's dismissal, bowled by Joe Leach for 15, sparked off a slump to 48 for four, one of the wickets falling to D'Oliveira.

Varun Chopra (10) was run out while Tom Lewis (eight) and Patel (11) also came and went but Clarke, Evans and Javid all played a major part to guide the Bears to victory.

Clarke said: "Obviously we are delighted for the two points. We have not had a great record here. We have struggled on Worcester wickets.

"Again it was an attacking wicket, we felt they probably got 20 more than they should have done. But we felt that we could take it deep with our batting line-up and that's what we did.

"There was a little bit of consolidation in the middle period. Again I think that's the wicket, you can't take too many risks. Laurie Evans has come and played an amazing knock.

"Sometimes I have to come in and throw the bat but I had a bit more time today and batted all the way through."

Worcestershire assistant coach Matt Mason said: "It was disappointing to be on the wrong end of the result. In these games there's always plenty of entertainment. I thought it was a really good game of cricket.

"It was a tough pitch to bat on. I felt that when we came off we had enough runs. Rikki Clarke played a terrific innings but sometimes you come up against a player on his day to win a game for his team. That's what Rikki did tonight.

"He was happy to knock it around for a couple of singles and pick up the twos and the odd boundary. Unless we got him out, he was always in apposition to do what he did. Laurie Evans also played a an explosive innings."