Arsenal brought Leyton Orient back to reality at the Emirates on Wednesday, while Manchester City advanced at the expense of Aston Villa.The Gunners, who fell victim to a last-gasp equaliser in their trip to Orient in the FA Cup fifth round, ensured there would be no such surprises in the replay with an emphatic 5-0 thumping of the League One outfit.Danish striker Nicklas Bendtner endeared himself to Arsenal boss Arsene Wenger with a hat-trick, accompanied by goals to Maroune Chamakh and Gael Clichy, to set up a tantalising visit to fellow Premier League title contenders Manchester United in the quarter-finals.Wenger, whose hopes of an ambitious quadruple of trophies were dashed when Arsenal lost to Birmingham City in the Carling Cup final on Sunday, retained only Tomas Rosicky from that side and handed debut starts to 19-year-old midfielder Conor Henderson and 18-year-old defender Ignasi Miquel.If the Gunners were not showing respect to Orient in their make-up it certainly did not affect their attitude on the pitch, and after bursting out of the blocks they deservedly took the lead in the seventh minute through Chamakh.The Moroccan striker, struggling for regular first-team appearances behind the likes of Robin van Persie, Theo Walcott and Andrei Arshavin, tapped home from close range after being picked out on Rosicky's surging run down the right.Bendtner, whose last goal came in Arsenal's 3-0 defeat of Ipswich Town in the Carling Cup semi-finals, nodded a superb header past Orient custodian Jamie Jones on the half hour and made it 3-0 with a quality individual move 13 minutes later.Bendter completed his hat-trick - Arsenal's first in the FA Cup for 18 years - from the penalty spot shortly after the hour, and French defender Clichy put his own exclamation mark on the proceedings in the 75th minute, meeting Emmanuel Eboue's cross at the far post with his left boot.Manchester City set up a quarter-final meet with Reading after defeating a weakened Villa line-up 3-0 at the City of Manchester Stadium.Villa boss Gerard Houllier made eight changes to his first-team line-up, opting to leave the likes of Marc Albrighton, Ashley Young, Stewart Downing, Nigel Reo-Coker and Robert Pires warming the bench.The sweeping changes turned the fifth-round clash into a lopsided affair as Yaya Toure, Mario Balotelli and David Villa all found the net.Toure opened City's account in the fifth minute after Patrick Vieira's corner kick fell fortuitously into his path and Balotelli nabbed his 10th goal in City colours 20 minutes later, collecting Toure's pass and volleying from 15 yards out.Silva, returning from an ankle injury, fired off a third goal in the 70th minute after being played in by Pablo Zabaleta's cross from the right.