IN a game dominated by masters in their teens and early 20s, the September years of 78-year-old Viktor Korchnoi are a shock.

But even Korchnoi was stunned when he only drew a reunion match last month with his longtime rival, Boris Spassky.

After all, Korchnoi easily beat Spassky 6-4 in another match 10 years ago. Four years later, Spassky gave up competitive chess because he couldn’t take “the nervous pressure,” while Korchnoi continued to win prizes.

The 72-year-old Spassky was a big underdog in what was billed as a “Match of Giants” in Kalmykia, Russia, but managed a 5-5 tie.

The mystified Korchnoi said his skill may have declined since 1999 “but somehow Spassky is playing better.”

The old Spassky was evident in the fifth match game when he found the strong 9 . . . Qd7! to support . . . f5 and its threat of forking pieces with . . . e4.

After 11 e4, Black shot back 10 . . . g5! with the idea of 11 . . . g4 12 Ng1 Nd4, which would give Black a dominating position. Black easily refuted Korchnoi’s early-desperation 13 Nxe5.

Spassky said he managed to get back into shape during the match because “Viktor is a good trainer.”