Sinner withdrew from the match against Félix Ojealiasim (35th, Canada), a quarterfinal scheduled to be held in Madrid, Spain, on the 2nd (Korea time).
Sinner, who won the Australian Open, his first major tournament this year, did not challenge for the semifinals due to back pain.
Alcaras suffered a 1-2 (6-4 3-62-6) upset in the quarterfinals against Andrey Rublev (ranked eighth, Russia).
Alcaras, who recently won the tournament for two consecutive years, sought to win the Madrid Open for the first time in three consecutive years, but failed to achieve his goal.
Alcaras recently played in the tournament about a month after the Miami Open in March due to a right arm injury.
Rublev will meet Taylor Fritz (13th, USA) in the semifinals, and Ojealiasim will compete with Daniil Medvedev (4th, Russia) and Izzy Rehetska (31st, Czech Republic) to advance to the finals.
Rublev has advanced to the semifinals eight times in the singles of the Masters 1000 Series, but won only once in last year's Monte Carlo competition.
BY: 사설토토