One interested spectator was Celtic manager, Neil Lennon, presumably looking at Michael Morrison.
Ben Alnwick returned in goal, Jordan Cousins was given a well deserved rest but Chris Powell fielded a strong side.
A few miles away in Swindon, striker Michael Smith, was discussing a permanent move to the County Ground.
The game was a drab affair for the first 35 minutes, with the play littered with poor passing from both sides. Though Oxford barely posed a threat all night, it took Charlton a while to get into their stride.
Two pieces of quality in the space of three minutes effectively ended the game as a contest. After 35 minutes, Callum Harriott clipped the ball to Simon Church. The Welsh striker shielded the ball until he played it into the path of Yann Kermorgant. The Frenchman thundered in a left foot shot which Oxford keeper, Ryan Clarke, got his left hand to, but such was the power, Clarke could not prevent the ball hitting the back of the net.
Three minutes later, Lawrie Wilson played the ball into Church’s path. Jake Wright slipped, leaving Church clean through on goal. Church drew the keeper, but unselfishly squared the ball for Danny Green to score from close range.
A typical Kermorgant free-kick, just before the hour mark, completed the scoring. Kermorgant curled the ball round the wall from 30 yards.
There was still time for Diego Poyet to come on for his debut. The yougster was serenaded on to the pitch with, “He’s better than Gus,” by the travelling fans.
So the Addicks gained an ultimately easy victory and will now face Huddersfield in the Fourth Round on Saturday.
Charlton: Alnwick; Wilson, Morrison, Dervite, Evina; Green, Stephens (Poyet 82), Jackson, Harriott (Pritchard 68); Church, Kermorgant (Sordell 76).
Subs (not used): Phillips, Wood, Lennon, Pigott.
Goals: Kermorgant 35, 59, Green 38.
Subs (not used): Rose, Marsh, Long, Lynn, Shama, Bevans.
Booked: Mullins 66 (foul).
Referee: David Coote (Nottinghamshire).
Att: 3,225