At Wimbledon this year, Venus appears to be in better form, but she is currently ranked World #16 while Serena has been World #1 for well over a year. Venus won her first match 6-0 6-0 and has not dropped a set. In contrast, Serena played one of the most dramatic matches of the tournament so far against Briton Heather Watson in the 3rd round, coming back from two breaks (0-3) down in the deciding 3rd set to somehow even the set at 3-all. Watson broke again at 4-all and served for the match and got 30-15 (2 point away from victory) before losing 6-2 4-6 7-5.
I still expect Serena to win this match on Monday but I suspect it may be a 3-setter.