During the six-hour, 29-minute spacewalk on Sunday, mission specialists Patrick Forrester and Steven Swanson successfully completed all the tasks assigned to them, including the activation of the ISS' new truss segment.
As the shuttle, scheduled to dock at 3:38 pm (0108 IST on Monday), closes in on the ISS, the stage is set for changes at the station and for its crew members.
Williams, 41, is also set to break astronaut Shannon Lucid's record for the longest stay in space ever by a woman -- 188 days and 4 hours -- on June 16, three days before Atlantis brings her back to Earth.
The forecast for Friday morning is for light winds and a zero per cent chance of weather prohibiting the loading of propellants into the external tank.
Williams will be in rehab for at least 45 days, depending on her overall health condition, after which both her parents will join her in Houston, where she has been living since 1998 after being selected as astronaut by NASA.