West Ham United midfielder Gary O'Neil has warned his teammates that going to Stamford Bridge to face Chelsea is still a tough test for any side.
The Hammers ended a run of back-to-back defeats with a win over Stoke City in their last game but now face the daunting prospect of an away trip to the Blues.
O'Neil told the club's official website: "I went to Chelsea a few times with Portsmouth and we did okay on quite a few occasions but they had a fantastic team then.
"I'm not saying they don't now but those were the Jose Mourinho days with the likes of Arjen Robben, Damien Duff, Claude Makelele and Frank Lampard and all that.
"Hopefully we can do a good job on Sunday and take a step closer to guaranteeing our Premier League survival for next season as early as possible."
West Ham are currently 12th in the Premier League, nine points clear of the relegation zone.
