Heather Watson continued the defence of her Monterrey Open title with an impressive victory over sixth seed Ekaterina Makarova.

Watson triumphed 6-4 6-1 to set up a quarter-final clash with top seed Angelique Kerber.

The first set saw both players hold serve throughout the first nine games before Watson broke Makarova in the decisive tenth.

Although the score-line of the second set appeared more decisive, Makarova still made Watson work for her victory.

After Watson broke the Russian to go 3-1 up, she let slip a 40-0 advantage in the next game as Makarova fought back to deuce before eventually succumbing.

Watson had Makarova at break point again in the next game with a 0-40 advantage, but Makarova fought back to deuce before Watson took it.

The match ended with another long battle at deuce, with Watson converting her sixth match point for victory.