Steve Bruce admitted that Newcastle United were a "shadow" of the team that beat Everton last week as they collapsed at Southampton.
The Magpies were well beaten by the team that lead the Premier League, and now have a two-week inquest during the international break.
Bruce said afterwards:"It was a difficult evening for us against a very good Southampton team but we didn't do enough.
"We weren't aggressive enough and we found it very difficult.
"The goals we gave away probably summed up our evening.
"We gave it away far too cheaply and far too often.
"To do it you have to be good with the ball and make sure you look after it better than we did. That's why the players play at this level because they are expected to."
Bruce admitted he feared the worst after a sloppy start at St Mary's.
He said: "From six minutes in we gifted them the first goal then it was a difficult night all round. We were nowhere near where we were five days ago.
"That's my biggest issue - that we go up and down. It was a poor, poor performance.
"We were a shadow of the team I saw against Everton.
"We have to make sure we're better against Chelsea. There's a few shirts available, a few place up for grabs.
"We had to play it forward quickly and off the front but we just couldn't do it. It was a really difficult evening.
"We were beaten by the better team."
Hinting on the likely inquest back on Tyneside, Bruce said: "There's always going to be a reaction but that reaction is too often.
"That inconsistency is what nags at me."
