Three-time Miami Open champion Venus Williams was forced to save three match points against Kiki Bertens before moving into the tournament's last 16 on Sunday.
Williams came through a topsy-turvy match 5-7 6-3 7-5 but only after surrendering a 5-0 lead to lose the first set, then rallying from 1-4 down in the decider to take the match.
Williams' win sent her through to the Miami Open last 16 for the 15th time in her career and she will next face Britain's Johanna Konta who continued her fine return to form.
Konta, whose game has suffered since her loss to Williams in last year's Wimbledon semi-finals, beat Belgium's Elise Mertens 6-2 6-1 in just 65 minutes.
Sixth seed Jelena Ostapenko also booked her place in the fourth round with a 6-2 7-6 (3) win over Beatriz Haddad Maia of Brazil.
Australian 21st seed Ashleigh Barty was a 6-4 6-3 winner over Petra Martic of Croatia, while Monica Puig and American qualifier Danielle Collins were other early winners.