She was the only quarter-finalist from previous year to reach the last eight and is now through to her second grand slam semi-final having not dropped a set.
The 31-year-old rapper cheered on Williams during her quarterfinal match at Wimbledon against Camila Giorgi on Tuesday, where he was clearly completely invested in the game judging by his passionate reactions from the stands.
Williams dropped her first set at this tournament as the 52nd-ranked Giorgi produced an impressive display of power and accuracy in the opener.
She gave birth to daughter Olympia in September.
Dutchwoman Bertens, who had gained an appetite for eating up higher-ranked players having beaten ninth seed Venus Williams and number seven Karolina Pliskova in the past week, appeared set to swallow up another when she won the first set.
Williams needs to beat two seeded opponents to win her 24th major title, tying Margaret Court's record for Grand Slam wins.
It's okay, Serena, just keep your eyes on the prize at Wimbledon!
Her dance of delight signalled the end of Giorgi's threat as Williams raced to the finish line.
Del Potro will hope his second trip to the Wimbledon quarter-finals mimics his first run into the last eight.
And when Williams took the court for the second set, she did indeed look calm and composed - and roared back with a vengeance.
"At the French Open I had all that pressure, now it's gone", former junior Wimbledon champion Ostapenko said.
Goerges earned her spot in the semis with a three-set victory over Kiki Bertens 3-6, 7-5, 6-1. "But when I come here, I come here thinking that I can do a good result, no?"
Williams opted not to challenge when she saw a shot called long, although Hawk-Eye proved it was actually in, and Giorgi went on to bring up two break points, with Serena then mis-hitting wide to surrender the game.
"For me, there's so much farther I want to go to get back where I was, and hopefully go beyond that".
25 seed, Williams is in the Wimbledon quarterfinals for the 13th time.