However, the world No 5 from Japan was forced to labour against his unseeded Spanish opponent on the clay surface – and an arduous second set was, for long periods, going against him until the pendulum critically swung.
A straightforward first set evidenced the 25-year-old’s tag as favourite, as he immediately responded to losing his first service game by breaking Andujar back.
Thirteen winners and the same amount of unforced errors also showed, though, that Nishikori was not at his free-flowing best.
Andujar, the world No 66, broke Nishikori’s serve in the first game of the second set but the Japanese player was unable to respond as positively as he did in the first.
A beautiful backhand shot across court followed by a drop shot illustrated Andujar’s growing confidence as he forced Nishikori into laborious holds of serve.
But as Andujar wasted shots, Nishikori registered the elusive break to make it 4-4 at which point the result seemed imminent.
He held serve in the next game easily before a thumping return of serve down the line broke Andujar’s service game and his resistance.
Nishikori, who??is the only non-Spaniard to win the event in the past 14 instalments, was??extending his personal record against Andujar to 3-1 with the win.
The title is the ninth ATP accolade of Nishikori’s career and his second of the season.