Midfielder Alan McCormack reckons Brentford must take a long hard look at themselves after Tuesday's embarrassing Capital One Cup mauling at the hands of League Two Oxford United.

Head coach Marinus Dijkhuizen's experimental side - featuring record signing Andreas Bjelland and fellow Danish international Lasse Vibe - crashed 4-0 at home to exit the competition at the first hurdle.

Development squad players Courtney Senior, Jack O'Connell, Josh Clarke, Jermaine Udumaga, Josh Laurent and Courtney Senior were all thrown in at the deep end in a side that featured 11 changes from Saturday's 2-2 draw with Ipswich Town.

Rather than swim, the Bees were sunk by three goals - from Liam Sercombe, Danny Hylton and Kemar Roofe - in the opening 12 minutes before their misery was complete by John Mullins in the second half.

McCormack, a second half substitute, labelled the defeat as unacceptable and warned aspiring first team players had some soul searching to do.  

"I think there are a lot of people that shouldn’t really forget this night,” she told the club's website. 

“They’ve got to go out and have a look at their performance if they want to get in the first team.

"We made a lot of changes, but there are still a lot of players that are close to the first team and to put in a performance like that is not acceptable at any level.

“I don’t think we can be happy with what we’ve seen from the very first minute to the very last, we just weren’t good enough.”

He added: “We all make mistakes, we can all have a bad game but the minimum you need to put in is 100 per cent effort.

“If you run around, chase, hustle and bustle like Oxford did tonight, they deserved every bit they got out of the game. We didn’t have any heart, someone to put a foot in, make a tackle, up the tempo."