League Two club Oxford United made a mockery of the gap between them and Brentford of the Championship by winning 4-0 at Griffin Park in the League Cup first round.
Michael Appleton's men travelled to west London as huge underdogs, but were three goals up in the first 12 minutes through goals to Liam Sercombe, Danny Hylton and Kemar Roofe. Johnny Mullins then added a fourth early in the second half as Oxford coasted into round two.
Another League Two side, Luton Town, also beat Championship opposition, as they overcame Bristol City 3-1 at Kenilworth Road.
Shrewsbury Town enjoyed a fine run to round four of last season's competition, before losing to eventual winners Chelsea, and Micky Mellon's side - now of League One - got their 2015-16 campaign off to a flyer by beating Blackburn Rovers 2-1 at Ewood Park.
Burton Albion were promoted from League Two along with Shrewsbury last season, and they also defeated a Championship outfit - Bolton Wanderers losing 1-0 at home to Jimmy Floyd Hasselbaink's men.
Hartlepool also registered a shock, winning 1-0 at Fleetwood Town, but Queens Park Rangers were not denied at Yeovil Town - Chris Ramsey's team running out comfortable 3-0 victors.
Tom Bradshaw was Walsall's hero as he completed his hat-trick in injury time to snatch a dramatic 4-3 victory at Nottingham Forest.
There were four goals in extra time at Accrington Stanley, who held Championship side Hull City to a 2-2 draw after 120 minutes before the latter won on penalties.
Sheffield Wednesday, Charlton Athletic and Northampton Town picked up easy wins, while Cardiff City, Birmingham City, Peterborough United, Gillingham, Port Vale and Rotherham United also went through.
Carlisle United, Reading, Barnet, Rochdale, Barnsley and York City are in the hat for round two, while the other teams to progress on Tuesday were Bury, Wolverhampton, Fulham, Exeter City and Brighton and Hove Albion.
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