The 17-year-old was playing in her first grand slam quarterfinal, but trailing 4-0 in the second set, a frustrated Gauff smashed her racquet on the clay court after she double faulted.
Gauff ran her opponent close in the opening set, with Krejcikova needing a dramatic tiebreak to gain the upper hand in the match.
In the second set, the Czech player ramped up the pressure on her younger opponent, winning the first five games without reply.
But the American showed experience to belie her age, saving multiple match points and winning three straight games to make things nervy before Krejcikova claimed the second set’s decisive ninth game to reach the semifinals.
More to follow