Westbrook supplied 27 points, nine assists and seven rebounds while Durant chipped in with 25 points and eight boards as Oklahoma City notched an emphatic win to open the best-of-seven Western Conference semifinal series.
James Harden donated 17 points off the bench for the Thunder, who led by as many as 35 points in the rout.
The Lakers were led by Andrew Bynum with 20 points and 14 rebounds.
Kobe Bryant added 20 points for Los Angeles, which will seek to bounce back in Wednesday's Game 2 at Oklahoma City.
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