Robert Sanchez's grip on the Chelsea number one jersey is looking increasingly fragile after a costly error in the Premier League opener against Fulham raised fresh doubts about his reliability between the posts.

Sanchez was beaten by a Josh King strike in the first half — a finish that registered just 0.07 xG and 0.07 xGOT on FotMob's metrics. In practical terms, that figure means a top-flight goalkeeper would be expected to save that effort 93 times out of every 100. That Sanchez did not was impossible for manager Xabi Alonso to ignore.

The goal handed Fulham an equaliser and reignited a debate that has followed Sanchez throughout his time at Stamford Bridge. This was not an isolated lapse; the Spanish goalkeeper has been responsible for several high-profile errors during his Chelsea career, a number of which have cost his side directly.

A position already under pressure

Sanchez's vulnerability is not new. During the early months of Liam Rosenior's tenure last season, he was dropped in favour of Filip Jorgensen before eventually reclaiming the starting berth. Now, under Alonso, he faces another uphill battle to convince a new manager of his credentials.

His standing within the squad has also shifted. Until recently, Sanchez — at 28 — was the oldest member of Chelsea's first-team group, a distinction that carried a certain leadership weight. That status has been diluted with the arrivals of Jordan Henderson and Danny Welbeck, two experienced professionals who now provide seniority and authority in the dressing room.

Penders waiting in the wings

The more pressing challenge for Sanchez may come from within. Mike Penders, returning from a loan spell at Strasbourg, has emerged as a credible alternative. The young Belgian's statistics from his loan were in line with expectations, and he impressed with his composure and distribution — an attribute long considered one of Sanchez's primary strengths.

If Penders can offer comparable quality with the ball at his feet while presenting a longer-term ceiling, Alonso may decide the time has come to hand the Belgian a genuine run in the side. For Sanchez, the margin for further error at Chelsea is narrowing.