
The 30-year-old was once again less than convincing in her victory, two days after labouring in a first-round win over Ukrainian Grand Slam debutant Oleksandra Oliynykova.
Keys took 23 minutes to claim the opening set with a confident display that saw the American hit seven winners and convert all three break points against her compatriot in a one-sided start to the contest.
But the current world number nine allowed doubts to creep into her game in the second set, handing Krueger two breaks in serve with a succession of double faults that allowed the 21-year-old to open up a three-game lead.
Keys responded, however, by winning five games in a row to close out the match and progress to the next round.