Oxford captain James Constable described his side's second-half performance against Macclesfield as "not acceptable".
The U's threw away a 2-0 half-time advantage at Moss Rose to lose 3-2 and Constable wasn't happy with the poor showing.
"We've got to start taking responsibility," he told the Oxford Mail.
"We've been on a good run away from home, not losing a game, and we've come here and in the first half were absolutely coasting - we could have had five or six - and then we turn out in the second half and perform like that. It's just not acceptable.
"It was comfortable. You don't expect to lose a two-goal lead, especially away from home, at half-time and concede in the manner we did. None of their goals were good ones, just some poor defending."