The defending champion Sweeting had his chances, but didn’t take them as he failed to convert any of the six break point opportunities he had against Isner. That proved costly for him and the second seed Isner punished him for closing out the match in two tiebreaks.
Isner will play wild card holder and third seed Feliciano Lopez next, who got through to the semis as his opponent Carlos Berlocq of Argentina retired due to a lower leg injury at 6-4 2-2 in Lopez’s favour.
The Saturday’s semifinal will mark the third meeting between Isner and Lopez, with their current head to head standing at 1-1.
Should either of them win the Houston trophy, it will be the first clay court title of their career.
In the other semifinal, Juan Monaco of Argentina will face the American qualifier Michael Russell.