Chambers transitioned into the senior ranks soon after, taking the 100 m silver medal behind his British teammate Darren Campbell at the 1998 European Championships. He achieved a new personal best in September at the 1998 IAAF World Cup with a run of 10.03 s for third place and won a relay gold medal. At the 1998 Commonwealth Games he was a 100 m semi finalist and set a games record as part of the 4×100 m relay team. His ability attracted the attention of former sprinter and Commonwealth Games gold medallist Mike McFarlane, who became his coach. He came first in the 100 m in the 1999 European Cup, then at a meet in Nuremberg he became only the second European sprinter (after Linford Christie) to break the ten second barrier with a time of 9.99 s. Fellow British sprinter Jason Gardener scored a time of 9.98 s in Lausanne soon after, becoming the third Briton to break the barrier. In spite of this, Chambers remained some distance behind his North American counterparts.