The United States' John Isner is through to the Miami Open final ©Getty Images

The United States' John Isner ended Juan Martín del Potro’s pursuit of a second successive title as he claimed a straight-sets victory to reach the final of the Miami Open. 

Isner will take on fourth seed Alexander Zverev after the German beat Spain’s Pablo Carreño Busta. 

The big-serving American hit an impressive 39 winners to dispatch his Argentinean opponent 6-1, 7-6 at the Crandon Park Tennis Centre. 

Defeat for Del Potro ends his winning run and means he is unable to add to his triumph at the Indian Wells Masters earlier this month. 

Isner will bid for his first Association of Tennis Professionals (ATP) Masters 1000 title on Sunday (April 1). 

"I am so happy," the 32-year-old said. 

Juan Martin del Potro's winning run came to an end today ©Getty Images
Juan Martin del Potro's winning run came to an end today ©Getty Images

"He [Del Potro] is so tired and has played so many games, and although the first set was quick, I knew it wouldn't be like that in the second. 

"I have played a lot of big matches and not been able to get such a good start - but I am playing some of the best tennis I have played in such a long time." 

Zverev wasted little time in booking his place in the final as he recorded a 7-6, 6-2 success against Carreño Busta. 

The tournament continues tomorrow with the women’s final as American Sloane Stephens clashes with Jeļena Ostapenko of Latvia. 

It will be a meeting of two of last year’s Grand Slam winners as Ostapenko clinched the French Open crown and Stephens lifted the US Open title.