Los Angeles - Nick Kyrgios rallied from the first set loss to defeat unseeded American Bjorn Fratangelo 6-7 (2/7), 6-1, 6-2 in the second round of the US men's clay-court championship.
The 22-year-old Australian fourth seed hammered 21 aces and broke Fratangelo's serve four times in the one hour, 32 minute match.
Kyrgios is making his debut in the event and is seeking his first career clay-court title.
He has been hampered by injuries this season, pulling out of Rotterdam, Delray Beach, Indian Wells and Acapulco tournaments with back and elbow problems.
He returned for the Miami Open last month where he reached the fourth round before losing to Germany's Alexander Zverev.
Kyrgios advances to the quarter-finals where he will play Ivo Karlovic who eased past qualifier Denis Kudla 7-5, 7-5.
Results from ATP Tour US Men's Clay Court Championships in Houston, Texas on Wednesday (x denotes seed):
Ivo Karlovic (CRO) bt Denis Kudla (USA) 7-5, 7-5
Tennys Sandgren (USA x8) bt Nicols Kicker (ARG) 6-2, 7-6 (7/3)
Guido Pella (ARG) bt Sam Querrey (USA x2) 2-6, 7-6 (7/4), 7-6 (7/3)
Nick Kyrgios (AUS x4) bt Bjorn Fratangelo (USA) 6-7 (2/7), 6-1, 6-2