Simona Halep has warned her rivals she's playing her best tennis since last winning Wimbledon as she homes in menacingly on lifting the Venus Rosewater dish again.

The Romanian sounded like a woman whose tennis life is beginning again at 30 after the way she disarmed one of the WTA tour's young guns, Amanda Anisimova, 6-2 6-4 on centre court to reach the semi-finals on Wednesday.

Halep said she felt emotional to be back in the last-four after some difficult days since she rocketed to the title at SW19 in 2019 with a career-defining demolition of Serena Williams.

She effectively dismantled Anisimova in the same fashion on centre, dominating until a late fightback from the 20-year-old American gave her a few jitters near the finish line before she booked her semi-final date with Kazakhstan's Elena Rybakina.

"I'm very emotional right now, because it means a lot to be back in the semis," Halep said after winning her 12th match in a row at Wimbledon in a run that stretches back to 2019.

After the 2020 tournament was abandoned because of the pandemic and she missed last year's edition with a calf injury, Halep is seemingly making up for lost time, having not yet dropped a set and conceding just 28 games en route to the last four.

"I struggled a lot last year," Halep said, "And now I'm just trying to build my confidence back."

The former world No.1 is certainly doing a good job, with this year's 16th seed looking hard to back against as she moves into her third Wimbledon semi-final and seeks to lift her third grand slam crown after also winning the French Open in 2018.

Tunisian world No.2 Ons Jabeur features in the other semi-final, up against her great friend, the surprise packet Tatjana Maria, a mum-of-two who can't quite believe that she's made it to a grand slam last-four date for the first time.

But Halep reckons she's back to her best as she prepares to tackle Kazakhstan's first-ever women's semi-finalist Rybakina, the 17th seed who outstayed Australia's Ajla Tomljanovic 4-6 6-2 6-3.

"I'm very emotional right now, because it means a lot to be back in the semis," Halep said.

"It's definitely the best tennis I've played since 2019 when I won here. The tennis is here; I just have to believe."

Halep's improvement after an injury-hit 2021 season has been obvious since she began working with Serena Williams's old mentor Patrick Mouratoglou in April.

The match against Anisimova looked to have been as straightforward as her first four wins at SW19 this year as Halep simply dominated a dangerous opponent, who'd gone into the match with a tournament-leading 108 winners.

But when being completely outclassed, the American went for broke - and broke - as Halep served for the match at 5-2.

Anisimova even earned three more break points at 5-4, but fine serving came to Halep's aid as she won five points in a row to take the match in just 63 minutes.

"She could crush the ball in the end, and I didn't know, actually, what to do," Halep said.

"But I just believed in myself. I said that I have to stay there, strong on my legs."