The striker was on the score sheet during Saturday's 2-2 draw with Everton at the DW Stadium but Martinez was pleased with his all round performance.
Di Santo has been carrying a knock as well and Martinez says the international break will now give him the chance to recover fully for the game against Swansea.
"Franco is still recovering from his injury, but was desperately trying to get through 90 minutes after the injury picked up at Old Trafford, and he picked up one or two knocks during the game but nothing serious," Martinez revealed.
"I thought he showed incredible energy and levels in his play, lasting 70 minutes and will recover now to be fully for the next game against Swansea City."
Martinez was also pleased with the performance of Arouna Kone, who also scored, and thinks they will form a fruitful partnership.
"The partnership and link-up play between the attackers was impressive and they've got a real mix of style and power which creates problems for any side," he added.
"Their play was a real highlight in the first-half, whenever we got into a dangerous position they looked like scoring and it's a real strength to have that kind of threat in your play."