Just a few minutes before midnight, the top seed in Toronto finally registered his second victory of a rain-bedeviled day filled with frustrating delays.  As the weather wreaks havoc and the tournament shrinks into a few intense days, physical fitness becomes a critical factor during a week already filled with withdrawals in the wake of the Olympics.  At the end of the mayhem, calmer skies should await for the four survivors as the week limps to its conclusion.

Djokovic vs. Tipsarevic:  Despite the disappointment of leaving London without a medal, the world #2 has rebounded as well as one could have expected at a tournament that he has won twice, although never in Toronto.  Able to withstand the quirky Tomic and the revitalized Querrey in straight sets, Djokovic battled through a tense three-setter against Haas, who started the year outside the top 200 but could end it in the top 20.  Defying the merciless advance of time, the former world #2 surrendered his serve just twice in three sets and may have sapped the Serb’s strength for another draining affair against his countryman.  Djokovic has lost two of his last four meetings with Tipsarevic and won the other two by narrow margins, including a pair of tiebreaks that they split at last year’s US Open before the older man retired.  On the other hand, Tipsarevic’s two victories at London and Madrid came on occasions when his more famous compatriot lacked motivation or willpower to compete at his best and accepted defeat with scant resistance.  Since the pair share many of their strengths, including sparkling backhands down the line and the ability to redirect groundstrokes throughout rallies, their meetings have hinged upon execution.  In that area, Djokovic generally holds the advantage because of his heavier strokes, superior first serve, and greater stamina on both physical and mental levels.  If the last of those assets abandons him after an exhausting Friday, however, Tipsarevic might advance a round further this year than he did in Montreal, where a semifinal in 2011 catalyzed his current career-redefining surge.

Gasquet vs. Isner:  In a single splendid day, the Frenchman defeated not one but two top-15 opponents in Berdych and Fish.  Not known for his durability, Gasquet survived a weak first set in his second match to outlast the American who had won three straight meetings from him on hard courts.  During this season, he has improved significantly in his ability to mount comebacks after losing the first set, reversing his notorious habit of accumulating large leads and then watching them evaporate.  Curiously, the player who lost the first set won both previous encounters between Gasquet and Isner, and the eventual winner either saved match point or came within two points of defeat before capturing the momentum in a second-set tiebreak.  Against essentially a mirror image of himself in Raonic, the towering server advanced more efficiently than he did earlier on Friday, struggling to control his formidable weapon initially but mastering it in time to defeat Kohlschreiber in three sets.  Having reached the final at Indian Wells, where he upset Djokovic, Isner continues to compile experience in such moments that makes him increasingly dangerous.  But the Frenchman has reached the Rogers Cup final before and could take time away from this ponderously moving opponent with his agility at the net.  Gasquet’s backhand should expose Isner’s far weaker wing with ease, so the American will hope to strike quickly with his forehand when his serve does not win the point outright.  He often has struggled to recover from physically arduous tests, which can slice some pace from his serve, although playing two matches in one day still falls far short of his exploits at Wimbledon two years ago.