Despite a host of injuries, Der BVB took a huge step towards reaching the last 16 of the Champions League on Tuesday with a win in the Portuguese capital.
Weigl scored what turned out to be the decisive goal just before the break, gliding past a couple of defenders before firing in from 25 yards out.
The 21-year-old admits he was both delighted and shocked to finally score for the first time at senior level, especially as it came in such a hard fought victory.
He told the club's official website: "I am not really sure what I did for the goal. I am ecstatic that I finally found the back of the net. The manager keeps saying we have got to take our chances, and I managed that tonight.
"Sporting showed fight though in attempting to get themselves back into the game. But we gave our all, and we are happy that we made it over the line to win the game 2-1."