Cristiano Ronaldo scored his 21st goal of the season and his fourth in the Asian Champions League on Wednesday as his moment of magic proved decisive in Al Nassr beating Al Fayha 1-0 in an all-Saudi last 16 tie. At the Prince Faisal bin Fahd Stadium in Riyadh, the 39-year-old Portuguese star struggled at first to make much headway against a club sitting 14th in the Saudi Pro League. Al Fayha have been only one of two teams in the domestic league to prevent Ronaldo from scoring, and that streak looked like stretching to a third match. Then in the 81st minute, Ronaldo lunged forward and smartly volleyed the ball above the head of the advancing goalkeeper Vladimir Stojkovic following a quick 1-2 with Marcelo Brozovic.