Manchester United manager Sir Alex Ferguson has admitted that he cannot explain his side's problems in defence this season.
The Red Devils have conceded 28 goals in 19 matches in the Premier League.
"I can't answer that," Ferguson told reporters when asked why United are conceding so often. "I can't possibly answer it. Obviously, I don't think we'd be doing our job properly if we weren't assessing where we're losing goals.
"We've been analysing every possible detail to try and get a constant thread that tells me we need to do this but that just doesn't appear.
"Either we don't attack, which is not United's way, or we have to let our supporters live through the agony of 4-3s. We've not had a 5-4 yet or a 6-5. I think that would be even more exciting!"
Ferguson rallied his players to tighten at the back ahead of their clash with West Bromwich Albion at Old Trafford on Saturday.
"I said after the Reading game it had to stop," he said. "And I'm saying it again – it has to stop. But it won't stop.
"With this present team, it's just one of those seasons where we seem to be letting in silly goals."
United are currently seven points clear at the top of the league table.
