Son broke his right forearm on international duty in June and had been expected to miss about three months of action, potentially ruling him out of the Koreans' last two qualifiers against Iran on Aug. 31 and Uzbekistan five days later.
However, with the dynamic wide man coming off the bench in Spurs' 2-0 win over Newcastle United, South Korea coach Shin Tae-yong was hopeful Son would be fighting fit for the upcoming Asian qualifiers.
"He looked a lot better than I'd expected, though he still seemed a bit careful in physical battles," Yonhap News agency quoted Shin as saying on Monday.
"I wasn't sure if he would even be on the bench for the match. If he gets a couple more matches under his belt, then I am sure he'll be even better."
South Korea are second in Group A, seven points behind the already qualified Iran but only a point above third-placed Uzbekistan, who next play China away.
Only the top two from the group qualify automatically for Russia in 2018, while third earns a playoff against the third-placed team in Group B and another playoff against a side from the North American, Central American and Caribbean region.
Shin, who replaced Uli Stielike as coach after Korea's defeat in Qatar in June, also included Ki Sung-yueng in his 26-man squad, despite the Swansea City midfielder not expected to recover from a knee injury until mid-September.
Shin has said Ki's experience on and off the pitch is invaluable for the team and he would include him in the squad regardless of his fitness.
(Writing by Peter Rutherford; Editing by Amlan Chakraborty)
