Sinner’s last five-set set came at Roland Garros, where, as a heavy favorite for the title, he led Juan Manuel Cerundolo 6-3 6-2 5-1 before suffering a crushing defeat.
In his first official match since that surprise result, Sinner showed some understandable signs of nervousness and rust as he played Wimbledon for the first time without a grass-court competition under his belt.
Leading 40-0 at 4-4 in the first set, the top seed suddenly dropped nine points in a row to fall to the newcomer.
After surviving a disappointing error in the third set, he held off a set point in the ensuing tiebreak before Kecmanovic snatched three straight points to move within a set win.
It was also during the third set that the stains on Sinner’s white shoes began to turn red with blood, which he confirmed was caused by his fingernail.
“One fall is hard because you can get injured,” Sinner said. “I’m lucky because things can go wrong very, very quickly. I’m trying to still have faith in my movements. Also, in the third, fourth and fifth sets, it was very important to keep moving in a very natural way, which is what I did.”
“I’m very glad nothing happened.”
The defending champion stabilized and made progress in the sixth game of the fourth and fifth sets.
It was the first time Sinner had been stretched to five sets in the first round of a Grand Slam since the 2022 US Open.
“His plus-one shot today was very, very strong. Although I returned the ball very well at times, he always played the first ball very well and I struggled a little bit. So that’s something we need to improve on,” said Sinner, who failed to become the first reigning Wimbledon men’s champion to lose in the first round in 23 years.