Carlos Alcaraz said only "part of the job is done" after he secured the year-end world number one ranking by reaching the knockout stages of the ATP Finals with three straight wins.
Alcaraz was already assured of a semi-final place, after Alex de Minaur beat Taylor Fritz earlier on Thursday - but he would not be denied in his bid to edge rival Jannik Sinner in the race to be crowned the top-ranked men's player of 2025.
The 22-year-old Spaniard let out a huge roar as he achieved the feat by beating Italian ninth seed Lorenzo Musetti 6-4 6-1 - also ensuring he recorded 70 wins in a season for the first time in his career.