Marin Cilic (CRO) vs.  Jack Sock (USA)
My first day at the O2 Arena started with Sock warming up and ended with him winning his match.
Before the singles match, I was thoroughly entertained by the doubles match between Henri Kontinen and John Peers vs. Jean-Julien Rojer and Horia Tecau. Kontinen was a serving machine who maintained his focus the entire match. Rojer was doing great until they got to the tiebreak when he succumbed to nerves and donated two points to the opposing team when he failed to hold his serve. They lost the first tiebreak easily. They battled hard in the second tiebreak, but again they just could not take the all important step and came up short against the defending champions. Kontinen and Peers won 7-6(3), 7-6(6).
Sock led their head-to-head 2:0 going into this match; however, Cilic seemed bent on redeeming himself today. They traded breaks earlier and a late set break by Cilic would give him the first set. Sock was so furious, he hit a ball into the stands, incurring a warning from the umpire.
The second set was a head scratcher as Cilic lost his focus, his nerve and his serve twice to lose the set. Sock won the set without having to do much work.
Cilic took the early lead in the third set after a sloppy game by the American. Despite looking like his head was not completely in the game after he was broken, Sock perked up in time to break back and force a tiebreak. Sock won 5-7, 6-2, 7-6(4).
SOURCE OF IMAGES: serveandrally