The Spanish world No 1, enjoying a late-career flourish, dispatched Russia's promising Karen Khachanov 6-3 6-3 on the outside hard court in Beijing. Knowing that it was a tough challenge, Nadal lived up to the occasion and managed to edge through in the encounter, saving two match points to triumph in the first-round thriller.
"Just something came to my eye, that's all", said Nadal, who is chasing a sixth title this year.
"I think on return I did well".
'He is a player that I really like, a good friend on the Tour, ' said Nadal of the Bulgarian.
"I remember the match against him in the U.S. Open..."
Grigor Dimitrov also reached the final four as he saw off Roberto Bautista Agut 7-6 (5), 4-6, 6-2. But the American's shot at the net wasn't clinical enough and Nadal spotted the chance to lob the 6ft 11 Isner, not an easy feat. But still I didn't have the control of the match for nearly all the time. The eighth-seeded Australian won when opponent Steve Darcis retired with a neck strain while trailing 6-0, 3-0.
The loss was a big blow to Berdych's campaign to make it to the Nitto ATP Finals.
Second seed Alexander Zverev served seven aces as he beat Britain's Kyle Edmund 6-3 7-6 (3) in the day's last match and will meet Italy's Fabio Fognini in the next round.
To bump Garbine Muguruza from No. 1, the Romanian needs to reach the final.
Petra Kvitova, the two-time Wimbledon champion from the Czech Republic, faces Caroline Garcia of France in the other semi-final.
But the 27-year-old had five months out after suffering a wound to her playing hand when she was attacked in her home and hopes she might be fresher as a result. They face off for the second time this year having met at the start of the year in Melbourne, and the enthusiastic fans in Beijing will have a good show to watch as the two battle tomorrow afternoon at the National Tennis Stadium.