LONDON — For 368 points, for five sets, for a record 4 hours, 43 minutes — most quite marvelous, all with a berth in the Wimbledon final at stake — Novak Djokovic and Juan Martin del Potro put on a memorable show. Their baseline exchanges were lengthy and intense, accompanied by loud grunts of exertion and exhaustion, punctuated by the thud of racket string against tennis ball. In the end, as he almost always does lately, Djokovic displayed the stamina and fortitude to win a long-as-can-be match, edging del Potro 7-5, 4-6, 7-6 (2), 6-7 (6), 6-3 Friday to close in on a second Wimbledon championship and seventh Grand Slam title overall.