The 2009 champion, seeded ninth after a disappointing injury-disrupted 2016 season, grasped his chances ruthlessly to overcome the German in a little over two hours in the brutal afternoon heat at Melbourne Park.
A single break in each of the first two sets followed by some dominant serving was enough to give him a comfortable lead going into the third, which the Spaniard wrapped up with a 25th sizzling forehand winner.
The 14-times grand slam champion, who was watched by new coach Carlos Moya, moves on to a second round clash with Cyprus's former Melbourne Park finalist Marcos Baghdatis.
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(Reporting by Nick Mulvenney, editing by Amlan Chakraborty)
