Goalkeeper Michel Vorm's second-half penalty stop earned Swansea City their first point of the season against Wigan Athletic.
The home side dominated possession throughout, but struggled to create many chances after Ali Al-Habsi saved an early shot from Danny Graham.
Wigan's Jordi Gomez and Victor Moses both hit the bar in the second-half, before Swansea captain Williams' challenge on Gomez won the Latics a spot-kick, which Watson couldn't convert.
Swansea will next travel to Shrewsbury for the Carling Cup on Tuesday (August 23), while Wigan wait until next weekend to face QPR in the league.
