Friday night at the Italian Open, the Roman rain was getting heavier. As fans raised their umbrellas, Jannik Sinner and Daniil Medvedev were sludging their way through the seventh game of the third set of their semifinal.Medvedev, serving down 6-2, 5-7, 4-2, saved a break point at 30-40. The rain kept pouring. Medvedev got to Ad-40. The court was fine, according to chair umpire Aurélie Tourte, but the lines were getting dangerous.Sinner wanted to stop. Medvedev was unbothered. Tourte made her decision, and off the players went, the final action of the first chapter of a match that had initially promised precious little of the drama it ultimately delivered.Come Saturday, Sinner, the world No. 1, did what he needed to do, holding serve twice for a 6-2, 5-7, 6-4 win to reach his sixth consecutive ATP Masters 1000 tournament final, against Norway’s Casper Ruud. Should he win Sunday, he will have lifted all nine ATP Masters 1000 trophies, at 24. Novak Djokovic, the only other man to do that, did so when he was 31.Even in defeat, Medvedev demonstrated how hard he can push a player who so often looks immovable — and how hard it truly is to push him over the edge. In the past 52 weeks, Sinner’s average rally length in matches is 4 shots. On clay, it is 4.3.Friday night, Medvedev dragged the Italian up to 5.5, almost a 40-percent increase, according to data from Courtside Advantage. The slow, dank conditions made a difference too. But Medvedev is a master of attrition, and after being blown out in the opening set, he began to drag Sinner around enough that the Italian was constantly hitting shots on the run and after having to move, rather than dictating from a more settled position.