Almagro struck the first blow by securing an early break of serve, but Nishikori won the next three games to prevent the Spaniard from pulling ahead.
Despite making a number of mistakes on his serve, Nishikori managed to save two break points before converting a set point at the third attempt to strike a crucial blow to Almagro’s chances.
A dramatic third set saw both players trade two breaks of serve, and with the score at 6-6, Almagro somehow managed to save three set points to force Nishikori into a tie-break.
However, Almagro was unable to retain the momentum as Nishikori eased to a 7-1 success in the tie-break to pull further clear of the Spaniard.
Despite being given one of the tougher first-round draws, Nisikori appeared to be unfazed by Almagro’s aggressive approach as he looked to reduce the deficit.
There would be no late response from Almagro as Nishikori secured two breaks in the third on his way to a comfortable win.