Second half goals from Dexter Blackstock and Damien Delaney helped big-spending QPR come from behind to knock plucky Swindon out of the League Cup in a topsy-turvy first round clash.

Angelo Balanta's tap-in (32) had given Rangers the lead at the County Ground before Simon Cox's volley (34) and Billy Paynter's header (42) put Town 2-1 up at half-time.

But striker Blackstock's header just seconds after the break and skipper Delaney's 54th minute strike fired Ian Dowie's Championship side through to the second round.

QPR started brightly and Emmanuel Ledesma's deflected 22-yard strike fizzed just wide before Blackstock's 12-yard volley flew straight at Swindon goalkeeper Peter Brezovan from Lee Cook's ninth minute cross.

But Town soon settled into their stride and Sean Morrison planted a free ten-yard header wide from Jon-Paul McGovern's inswinging corner before Cox's near post flick from Anthony McNamee's cross was deflected just wide.

Paynter's super 15-yard volley was tipped wide by flying QPR goalkeeper Lee Camp on the quarter of an hour mark before Matthew Connelly's angled drive was well held by Brezovan at the other end in the 20th minute.

Rangers threatened again two minutes later when Blackstock wriggled free of Robins skipper Hasney Aljofree on the edge of the box but his 12-yard finish was too close to Brezovan.

The pacey Blackstock then looped a ten-yard header onto the roof of the net from Ledesma's deep cross.

And as the Championship side began to turn the screw, Ledesma's 20-yard free-kick was well saved by Brezovan before he and Blackstock fired long range efforts inches wide.

Blackstock went close again when he beat Brezovan to a long ball but, after nodding it past the Town stopper, the angle was too tight and his cross came to nothing.

But Balanta handed QPR a deserved lead in the 32nd minute when he bundled in on-loan Real Madrid midfielder Daniel Parejo's corner at the near post.

Swindon came back fighting and their efforts were rewarded when Cox equalised just two minutes later.

McNamee's cross was not properly defended by the QPR back-four and, after the ball had looped up into the air, Cox kept his eye on it superbly to swivel and volley low into the corner of the net from 12 yards.

The dangerous Ledesma broke the Robins offside trap but was denied well one-on-one by Brezovan, before Paynter put Town ahead on the counter-attack at the other end three minutes before the break.

McNamee whipped in a teasing cross and Paynter produced a majestic 12-yard diving header to plant the ball low past Camp and into the corner of the net.

Parejo curled a 25-yard free-kick against the outside of the post for QPR as Swindon clung on to their lead at the end of a breathless first half.

But Rangers didn't have to wait long to equalise as Blackstock made it 2-2 just 41 seconds into the second half, heading in Cook's cross from six yards at the far post.

Skipper Delaney put QPR 3-2 up in the 54th minute when he fired in the loose ball from close range after Ledesma's corner was not dealt with by the Town defence.

Cox thought he'd equalised for Swindon five minutes later but his tap-in from Lilian Nalis' shot was correctly ruled out for offside.

Moments later the towering Paynter's header from McNamee's cross shaved the far post as the Robins battled back gamely.

Swindon veteran Nalis glanced a seven-yard header over the bar from McGovern's corner in the 80th minute, before Delaney's strike from Parejo's corner was cleared off the goal-line by Jack Smith at the other end.

Aljofree fizzed a low 25-yard thunderbolt inches wide from McGovern's quick free-kick and Paynter's header shaved the post at the death as Town were left frustrated.

Swindon Town: Brezovan, J Smith, Timlin (Easton 75), Aljofree (c), McGovern (Peacock 84), McNamee, Casal, Nalis, Paynter, Morrison, Cox. Subs: P Smith, Easton, Joyce, Kennedy, Peacock, Allen, Amankwaah.

QPR: Camp, Delaney (c), Stewart, Leigertwood, Parejo, Blackstock (Di Carmine 70), Gorkss, Connelly (booked for foul 30), Cook, Balanta, Ledesma (booked for dissent 59) (Alberti 79). Subs: Cerny, Agyemang, Bolder, Ramage, Alberti, Di Carmine, Ainsworth.

Referee: Mr R J Beeby.

Attendance: 7,230.