A much-changed Arsenal struggled to break Oxford down during the first half of the clash.
However, they went on to net three times in the second half to book their spot in the 4th round vs Manchester City.
Now though, the FA have opened a spot-fixing investigation into suspicious betting patterns surrounding the booking of Oxford defender Ciaron Brown in Monday’s FA Cup defeat by Arsenal.
It is reported that the FA have a dossier of evidence regarding supposed corruption, including alleged phone messages before kick-off at the Kassam Stadium which claim that Brown would be booked in a betting scam that allegedly cost one bookmaker more than £1,600.
One message is understood to show a betting slip with around £200 staked on Brown being yellow-carded at odds of 8/1.
The 24-year-old Northern Ireland defender was booked in the 59th minute for fouling Bukayo Saka with the score at 0-0.