on march 7, 2018, in the first leg of the concacaf champions league quarter-finals, altidore scored in a 2–1 home win against mexican side tigres uanl. in the second leg, held on march 13, altidore helped create an own goal in an eventual 3–2 away defeat; the result enabled toronto to progress to the semi-finals of the competition for only the second time in their history, on away goals, following a 4–4 draw on aggregate. altidore scored a brace on march 30, in a 3–1 home win against real salt lake, which included his 50th goal for toronto fc. on april 3, altidore scored in a 3–1 home win over club américa in the first leg of the concacaf champions league semi-final. he suffered an injury in the seventh minute of the second leg, on april 10, at the estadio azteca, and was replaced by tosaint ricketts; the match ended in a 1–1 away draw, which saw toronto advance 4–2 on aggregate to the finals. he made his 100th cap for toronto fc on april 25, in the second away leg of the 2018 concacaf champions league final against chivas guadalajara, although he was later forced off with an injury; toronto won the match 2–1 to tie the score on aggregate, resulting in a penalty shoot-out, which toronto lost 4–2. altidore later underwent surgery to remove bone fragments from his foot, and it was announced that he would be sidelined for four to six weeks. he returned to action on july 21, in a 2–1 away win against chicago fire. on august 12, he was sent off after only 11 minutes in a 3–2 home defeat against new york city fc, after allegedly kicking defender alexander callens in the back of the leg. on august 15, in the second leg of the 2018 canadian championship final, altidore scored a hat-trick in a 5–2 home win over vancouver whitecaps to seal the title for toronto with a 7–4 victory on aggregate.