Bjorn Borg for the entire 1978 French Open and for the 1978 Wimbledon final against Connors in particular. He lost only 7 games in the W final. At the FO that year, he lost a total of 32 games and dropped no sets. I'd also include the 1976 W tourney, when he won the tourney without losing a set. (his first W title, beating Nastase in the final)
1978 Wimbledon
R128 Victor Amaya (USA) W 8-9, 6-1, 1-6, 6-3, 6-3
R64 Peter McNamara (AUS) W 6-2, 6-2, 6-4
R32 Jaime Fillol Sr. (CHI) W 6-4, 6-2, 6-8, 6-4
R16 Geoff Masters (AUS) W 6-2, 6-4, 8-6
Q Sandy Mayer (USA) W 7-5, 6-4, 6-3
S Tom Okker (NED) W 6-4, 6-4, 6-4
W Jimmy Connors (USA) W 6-2, 6-2, 6-3
1978 French Open
R128 Eric Deblicker (FRA) W 6-1, 6-1, 6-1
R64 Rick ***el (USA) W 6-0, 6-1, 6-0
R32 Paolo Bertolucci (ITA) W 6-0, 6-2, 6-2
R16 Roscoe Tanner (USA) W 6-2, 6-4, 7-6
Q Raul Ramirez (MEX) W 6-3, 6-3, 6-0
S Corrado Barazzutti (ITA) W 6-0, 6-1, 6-0
W Guillermo Vilas (ARG) W 6-1, 6-1, 6-3