Xabi Alonso hasn’t even officially started his job yet, and he’s already pumping the brakes on Chelsea’s transfer machine. The newly appointed manager has requested that the club hold off on any decisions regarding young centre-back Mamadou Sarr until he can personally evaluate the player during pre-season.

What’s happening with Sarr

Mamadou Sarr, a 20-year-old Senegal international, signed for Chelsea on June 9, 2025, on an eight-year contract. His journey since then has been the typical Chelsea young player odyssey. He made his debut during the Club World Cup in the summer of 2025, then was shipped out on loan to Strasbourg for first-team minutes.

That loan didn’t last the full season. Chelsea recalled Sarr in February 2026, and he got his first start for the senior team in an FA Cup match against Hull City on February 13, 2026.

RB Leipzig has reportedly expressed interest in Sarr as of June 2026. But Alonso’s intervention has put everything on pause.

Alonso’s fresh start at Stamford Bridge

Alonso was appointed as Chelsea manager in May 2026, signing a four-year deal that officially begins on July 1, 2026. He arrives after a 2025-26 season that featured multiple managerial changes. The Spaniard built his coaching reputation at Bayer Leverkusen, where he turned a perennial also-ran into a dominant force in German football.

Pre-season is set to kick off with a tour beginning on July 28, 2026, when Chelsea face Western Sydney Wanderers in Australia. That gives Alonso roughly a month from his official start date to begin working with the squad, including Sarr, before competitive football resumes.

Why this matters beyond one player

Sarr is still just 20, tied to the club until 2033 on that eight-year deal, and has shown enough flashes — his FA Cup start against Hull, his international experience with Senegal — to suggest the raw material is there. If he doesn’t impress during pre-season, a loan or permanent sale to a club like RB Leipzig becomes much more likely. Leipzig’s interest makes sense from their perspective, as the German club has long specialized in developing young talent.

Alonso is establishing early that he wants input on squad composition. Chelsea has burned through coaches at an alarming rate, and one common thread has been the sense that managers were handed squads rather than building them. The July 28 opener against Western Sydney Wanderers will provide early clues about how Alonso deploys Sarr and what tactical role the defender is asked to fill.