Give my dude a katana, and he’d effortlessly lop off your head like he was taking the top off a dandelion.

Del Potro, meanwhile, looks like he’s smacking you upside the head with a cast-iron pan. Indeed his forehand grip is so eastern—a relative rarity on the pro circuit these days—that he holds it about the same way you’d hold a skillet.

Only a giant can get away with this motion: at 6-foot-6, the Argentine looms so high above the net that he’s free to thwack it flat and hard down into the court rather than brushing up under the ball like his shorter opponents, who must generate enough topspin to keep their shots dropping inside the baseline. (Call it tall tennis privilege, but there are plenty of drawbacks to being that big, too.) In its best incarnations, the flat del Potro forehand gets deep in the court and loud on your television speakers.

Last night, the battle of pitiless forehand vs. backhand was won by the guy who actually had two functional groundstrokes. Due to a recovering wrist, del Potro appeared severely limited on the backhand side. At many junctures, even when he had Stan scrambling, he couldn’t muster his two-hander and had to resort to a backhand slice, sapping the furious pace out of the rally and allowing his opponent to stabilize the point. His death blow likely arrived in the third set when Wawrinka made a savvy adjustment on return games: he started hanging back for del Potro’s second serve, so he could let the ball drop and take a healthy swing at it, constructing more favorable points from the baseline. Wawrinka started to find his breaks and stole the last two sets for a 7-6 (5), 4-6, 6-3, 6-2 win, and a matchup against Kei Nishikori in the semifinals.