OXFORD United's FA Cup adventure came to a halt as Charlton Athletic did enough when it counted to win the third round replay.
A poor start to the game turned on two goals in three minutes, which put the visitors in charge at half-time.
Yann Kermorgant, who scored a late equaliser a week earlier to deny the U's and take the tie to a second game, opened the scoring, before Danny Green quickly made it 2-0.
Kermorgant's free-kick killed the contest before the hour mark as the Championship side made smooth progress.
United were left to reflect on a night where they were not outplayed, but failed to create anything of real substance in the final third.
Deane Smalley sets off on a run
It took almost 80 minutes before the hosts, who had thrillingly raced into a 2-0 lead in the first game, managed a shot on target as their cup run ended meekly.
Scott Davies and Josh Ruffels, impressive at The Valley, were restored to the starting line-up.
It meant United fielded the same side which began the first game between the sides, with the exception of Deane Smalley coming in for Tyrone Marsh up front.
The playing surface at the Kassam Stadium was much better than the mud bath at Charlton, but a rain shower before kick-off made the pitch greasy.
It contributed to an error-strewn first 30 minutes, as both sides repeatedly mis-placed simple passes.
The scrappy pattern of the game arguably suited the underdogs, who worked hard to put their visitors from the Championship under pressure.
It worked, but when they got the ball back United also struggled to do anything meaningful with it.
Scott Davies heads for goal at the end of the first half
It was summed up on ten minutes when they forced three corners in succession. Two failed to beat the first man, while the third was caught by goalkeeper Ben Alnwick.
If anything, Charlton were even less impressive on the ball.
But ten minutes before the break a long, hopeful ball forward gave Charlton a chance. Simon Church held off Michael Raynes and teed up Kermorgant, whose low shot from 20 yards had just enough power to beat Ryan Clarke.
It came out of the blue and within two minutes they had taken a firm grip of the tie.
Their appeared little danger from a looping ball just inside the United half, but Church beat Raynes to it and suddenly found himself clear.
The striker advanced deep into the area, drawing Clarke out before squaring unselfishly to give Green the easiest of tap-ins.
It gave Charlton a swagger as they indulged in an extended bout of keep-ball to end the half, but United emerged after the break with purpose.
A bright spell saw them push the Addicks back, without seriously testing them.
Twice they engineered decent positions, but poor final balls from Davies and then Newey let the visitors off the hook.
Charlton responded by putting the tie beyond doubt just before the hour mark, when Kermorgant curled in a beauty of a free-kick.
It effectively ended any hope of a comeback and the game wound down noticeably in the final half hour.
It all means United will host Torquay United in Sky Bet League Two on Saturday, while Charlton progress to visit Huddersfield Town in the fourth round.
Oxford Utd (4-3-3): Clarke, Hunt, Raynes, Wright, Newey, Davies, Mullins, Ruffels, Rigg, Constable, Smalley.
Subs used: Marsh (Constable 79), O'Dowda (Rigg 79).
Unused subs: Rose, Long, Lynn, Shama, Bevans.
Charlton (4-4-2): Alnwick, Wilson, Evina, Morrison, Dervite-Vaussoue, Green, Stephens (Poyet 81), Jackson, Harriott (Pritchard 68), Church, Kermorgant (Sordell 76).
Unused subs: Phillips, Wood, Lennon, Pigott.
Attendance: 3,225 (583 visitors).
Referee: David Coote (Nottinghamshire).