Sam Allardyce, the Newcastle United manager, issued a stark warning to his players after Saturday's 4-1 drubbing by Portsmouth sparked speculation over his future.

The club refused to dignify reports that owner Mike Ashley is lining up Mark Hughes, the Blackburn Rovers manager, as a replacement for Allardyce with a public response. Privately, they insisted the 52-year-old has the club's full backing.

"You cannot play football on ability alone," Allardyce said. "Sometimes we play football or rely on our ability too much to win a game of football. But you need much, much more than that.

"I don't think anybody really had that good a game, the lads themselves know that. Week in, week out, you cannot have a day off in this league. You have got to go to your full extent every single game.

"You have got to stick to the basics, and if you don't do that as a side you will never be resilient, you will never look organised, and you will never be a good side in possession or a difficult side to break down out of possession.

"Because we went 3-0 down so early a lot of the players lost their discipline and shape. We became very ragged and ultimately, we lost our football and passing game."

Newcastle's home form had laid the foundation for a promising start to the new manager's reign. Successive victories over Wigan Athletic, West Ham United, Everton and Tottenham Hotspur had gone some way to compensating for a less than impressive return on the road.

"We were looking very comfortable playing at home and defensively we were allowing our attacking flair players to go and create and score goals," Allardyce said. "But it has all gone out of the window. It's back to basics and back to square one. It's back to rolling our sleeves up and digging in.

"It doesn't need somebody like me, who has been in the game a long time, to say it was virtually put beyond our reach in the space of 12 minutes. Two defensive errors made life extremely difficult for us, and, of course, one wonder goal to begin with.

"We felt a little sorry for ourselves because they scored such a wonderful goal, and unless we get basic defending right, then life will be difficult for us."

Newcastle's problems are compounded by the loss of Nicky Butt through suspension after he collected his fifth booking of the season, while goalkeeper Shay Given is expected to be sidelined for up to three weeks with a recurrence of his groin problems.