It’s still the fall, but Roger Federer was in full Lion in Winter mode in the Basel final on Sunday. He grumbled. He muttered. He fist-pumped. He shook his head in disgust and bewilderment. He roared his approval of a winner before it landed. He slammed a ball into the ceiling after a miss, and did it again a couple of minutes later. He eyed a Hawk-Eye replay skeptically, told chair umpire Mohammed Jennati there was “no chance” one of his serves had been a let, and held up play before the final game because he heard noises.

This was the vocal, emotional, and often agitated Federer that many of his fans have wished to see in the past, and which has begun to pop up on occasion in recent years. It reminded me of the Federer who played Andy Murray in the semifinals in Melbourne earlier this year. On that day and today, Federer fell behind early, willed himself to even the score, but in the end had to bow to the younger, superior player on the day. Today that player was Juan Martin del Potro, who overcame Federer, and his home Basel crowd, for the second straight year, 7-6 (3), 2-6, 6-4.

The match began the way most of their matches have in the past: Del Potro tried to hit through Federer with his superior pace, while Federer tried to mix up his spins and trajectories enough to make del Potro uncomfortable and move him out of position. Del Potro imposed his will often enough to serve for the first set at 5-3, but Federer broke back by using a traditional tactic against the big man, the short slice backhand that forces him to bend. In the tiebreaker, though, everything went del Potro’s way. He opened with a net-cord winner for a mini-break, powered an ace when Federer got the score back to 3-4, and won the last two points by landing his ground strokes smack on the baseline.

But those were the last things that went the Argentine's way for the next 45 minutes. In the second set, Federer went toe to toe with him and imposed his own will. His forehand, so shaky for so long, had the liquid whip of old. He broke del Potro in his first service game with a winner from that side, and broke against for the set at 5-2 with two aggressive forehands and a fist-pump. The set was Federer’s, and the crowd was on its feet.

In Australia, Federer had played a similarly inspired fourth set against Murray, summoning all of his old brilliance to stay alive. But he had little left, emotionally or physically, for the fifth. I suspected something similar might happen today; but while Federer did lose the third set, he didn’t go fade away. This time he had a brief lapse in his opening service game, and del Potro made him pay for it. Up 40-15, Federer hit two of his five double faults on the day. At break point, he sent a routine ground stroke over the baseline, and sent another ball into the roof. He must have known something. Federer had left the door open, and del Potro is too good, and now too confident, not to drive through it. From there the Argentine won 14 straight points on his first serve and held five straight times for the match. When he needed a point, tennis’s Big Tank rotated the turret and brought out the big gun.

The title was del Potro’s fourth of 2013, and the momentum he created during the Asian swing will still be intact as he heads for the bigger, season-closing events in Paris and London. Federer, a busy week over and his emotions spent, was greeted with a long standing ovation from the home crowd. Their man had lost, but he’d let them know them how much he wanted to win it for them.