Alex Ferguson described watching his Manchester United side's defending in the topsy-turvy 4-3 victory over Reading on Saturday as agony.
United conceded three times in the opening 23 minutes of a rollercoaster first half at the Madejski Stadium but scored four times themselves before the interval to go three points clear at the top of the Premier League.
"It was agony, the worst defending of this season, and we needed to do something about it," Ferguson, who hauled off defender Rafael in a first half that often resembled a playground kickaround, told ESPN.
"I thought it was going to be a record score in the Premier League at halftime. It was unbelievable.
"We're needing to rescue the situation all the time. Fortunately we have players who can do that.
"We saw it through and had two really good opportunities from Robin (van Persie) to finish it off but I was just glad to get over the line. If we defend like that against Manchester City, I might need to play myself."
United have conceded the first goal numerous times this season and have had their defence breached 21 times as they struggle to cope with the absence of the injured Nemanja Vidic.
That is 10 more than champions City, whom they face at the Etihad Stadium next weekend.
In attack, however, they remain lethal.
Wayne Rooney scored twice, once from the penalty spot, on Saturday, while Van Persie's 10th league goal of the season, a typically cool piece of finishing, proved to be the winner as the second half petered out.
"We could have been battered today, but thankfully we are always scoring goals and that is rescuing us every time," Ferguson said. "Wayne was fantastic in the first half, as were Robin and Ashley Young. Reading couldn't control them.
"We should have finished the game off with some of the opportunities we had. In the first half, I said to myself that it would be a miracle if we win this one.
"I'm just glad that we did."
Reading led 1-0 through Hal Robson-Kanu before Anderson combined superbly with Young to equalise, and Rooney fired United ahead from the penalty spot.
Adam Le Fondre was given a free header to level for Reading before another set piece saw Sean Morrison make it 3-2 for the hosts. Rooney then turned in Patrice Evra's low cross before Van Persie's contribution to the scoring bonanza.
Sanity broke out in the second half as the goals dried up and United held on for the win that lifted them above champions City, who had gone top with a 1-1 draw with Everton.
In what looks like a two-horse title race United have 36 points from 15 games with City on 33.
The chasing pack of Chelsea, Tottenham Hotspur and West Bromwich Albion each have 26.
"I think it was important to win, knowing the results from earlier," Ferguson said. "But you have still got to win your game and today was a real cliff-hanger for us, but fortunately we got the three points."