LORIK Cana claims Sunderland’s players were “shocked” by their seven-goal humiliation at Stamford Bridge, but admitted the defeat was the continuation of a worrying trend that has developed in the last six weeks.

The Black Cats slumped to their heaviest defeat of the season as Chelsea ran riot, and with goalkeeper Marton Fulop making two excellent second-half saves, they could hardly have complained had the final margin of defeat been even wider.

The reverse made it eight Premier League matches without a victory, and while few could have envisaged so embarrassing an afternoon, Sunderland’s recent form has been alarmingly poor.

Cana accepts that while injuries and suspensions can be used as mitigating factors, they are inadequate explanations for so pronounced a slump.

“We are all shocked by what happened,” said the Sunderland skipper, who was forced to play as an emergency centre-half at Stamford Bridge. “We are all professionals and we know we have to be better than that.

We have a lot of fans who travelled on a long trip to London, and we are disappointed for them.

“This is not a one-off, it is a continuation of a run of matches that have not gone well for us. I don’t think the size of the defeat was expected, but the last month or six weeks has not been good enough.

“We have let ourselves down. There have been reasons, especially injuries and suspensions, but we have not been good enough.

Injuries and suspensions are part of football and we have to be able to deal with them.”

Nevertheless, Cana anticipates a marked improvement when a number of the club’s senior players return to action in this weekend’s FA Cup fourthround tie at Portsmouth.

Michael Turner will be available after completing a four-match ban, while midfielders Lee Cattermole, Andy Reid and Kieran Richardson should all be in contention for a starting spot after failing to make the squad on Saturday.

“Hopefully we can get some players back for the next game and get back to winning ways,” said Cana. “If we work hard, we can definitely turn this around.

“People talk about bringing players in, but in my opinion it is more important to get the players we already have fit. We have some very important players missing at the moment and we need them back.

“With all of our best players, we have a very good team, certainly a team that is good enough to finish in the top ten. But if two or three of those players are missing, it is a bit more difficult. You can get away with it for one or two games, but if it goes on longer, it is very hard to keep plugging the gaps.”

Sunderland are down to 13th now, the lowest position they have filled all season.

Having been touted as European contenders as recently as two months ago, the Black Cats are just four points above the relegation zone, and Cana admits the next month will be crucial in determining where their focus lies in the final weeks of the campaign.

Once next week’s FA Cup tie is out of the way, Sunderland’s next four matches pit them against Everton, Stoke, Wigan and Pompey – all teams in the table’s bottom 11 positions.

“We are not very far away from the relegation zone now,” said Cana. “But then on the other hand we are also not very far away from the top ten. The next few matches will probably decide which direction we move in. We have to pick up some points quickly. We have the cup game first, but we know what we have to do in the league."