West Ham United defender Matthew Upson has challenged new teammates Lars Jacobsen and Tal Ben Haim to make their positions their own.
Both players featured in defeat to Chelsea.
Upson told whufc.com: "We're four games into the season and hopefully that can now happen and we can set up with Lars, who is a solid right-back who knows his job. I liked the look of him on Saturday. I thought he did well. He's experienced, he's played a fair bit in the Premier League and he knows his job, so he looked good.
"I thought Tal did all right. His positioning is good and he uses the ball pretty well. We just need somebody to stamp their authority, as the manager then knows who his No1 and No2 centre-halves are and he goes with them when they are fit. I think every good team has that and in every position we need to have that kind of stability.
"We need to get that momentum going as a unit and stop conceding goals, which has been a problem for us."
