Follow The Athletic’s Wimbledon coverageWelcome to the Wimbledon briefing, where The Athletic will explain the stories behind the stories on each day of the tournament.On Day 1, there were slips and falls aplenty, a defending champion survived an upset, and Britain had a very rough day.How did the fresh grass affect play?Slipping on grass is always an occupational hazard for a tennis player, but especially at the start of a tournament when the courts are at their freshest and slickest.Sure enough, Day 1 of Wimbledon was defined to some extent by the slips — and those players who got away with them, and those who didn’t.Jannik Sinner, the world No. 1 and defending champion, was one of the lucky ones. He took a couple of falls, the second of which in the third set looked particularly awkward. Sinner was quickly back to his feet, though, and ultimately beat Miomir Kecmanović in five sets.Maja Chwalińska, this year’s French Open finalist, wasn’t so fortunate. The 24-year-old from Poland was up match point against Thailand’s Mananchaya Sawangkaew, leading 6-2, 5-2, when her legs buckled from underneath her, and she fell to the ground. Chwalińska took a medical timeout for an ankle injury at the end of the game and was clearly hampered by it for the rest of the match. She ended up losing 2-6, 7-5, 6-2 and said in a news conference afterward that she had also “got cramps everywhere.”Argentina’s Camilo Ugo Carabelli couldn’t even make it to the end of his match after a fall that also left him with an injured ankle. He had led by two sets to love but was forced to retire leading Spain’s Daniel Mérida 6-4, 6-3 2-6, 0-3. Canada’s Denis Shapovalov also hurt his shoulder hitting a low ball before slipping into the netting by the side of the court and was forced to retire against Pablo Carreño Busta.Novak Djokovic took a couple of falls in the early stages of his match against Yibing Wu but didn’t suffer an injury.It’s a situation that should improve over the next few days as the areas around the baseline become rougher and more worn, but being able to avoid injury when falling is a key grass-court skill.— Charlie EccleshareHow did Sinner survive a five-set scare?For a little while Monday, Sinner looked as though he was about to create a piece of very unwanted history. Down two sets to one against an inspired Miomir Kecmanović of Serbia, he was one set from becoming the first defending Wimbledon men’s singles champion to lose in the first round since Lleyton Hewitt to Ivo Karlović in 2003.The 24-year-old Italian was mixing woeful drop shots with regulation misses (Sinner made 54 unforced errors in the first three sets) against Kecmanović, who was serving brilliantly and skidding the ball through the court.When Sinner held a set point in the third set, Kecmanović produced extraordinary athleticism to fend him off at the net. As the players crossed one another at the change of ends, Sinner held out his hand to Kecmanović in respect for his opponent’s heroics:A couple of points later, Sinner was a set away from what would have been his second shocking loss in a row, after a heat-induced collapse against Juan Manuel Cerúndolo at the French Open last month when Sinner wilted from two sets and 5-1 up.