Career-long rivals Novak Djokovic and Rafael Nadal will face off for the 48th time on Saturday for a place in the final of the Indian Wells Masters after both produced fiery quarter-finals wins in sweltering conditions.
The Friday victories in 34 Celsius temperatures under the desert sun sends the pair into their second showdown of the season; Djokovic beat the Spaniard in the Doha final nearly three months ago.
Djokovic was tested in two sets by French threat Jo-Wilfried Tsonga, with the world number one Serb exploding into form in back-to-back tiebreakers to confirm a 7-6 (7-2), 7-6 (7-2) win.
"It was definitely very challenging to play in these kind of conditions with Jo that was in form this week," Djokovic said.
Nadal, seeded fourth, battled to earn his fifth semi-final placing in less than a year at the Masters 1000 level, with the Spaniard defeating Japan's Kei Nishikori 6-4, 6-3.
The women's final was set, with Serena Williams - who boycotted for 14 years - into her first desert title match since 2001 after beating Agnieszka Radwanska 6-4, 7-6 (7-1), her tenth in succession over the Pole.
Williams, who won seven straight games in a comeback after trailing 2-4 to improve to 23-1 at the event, , will face Victoria Azarenka a winner over Karolina Pliskova 7-6 (7-1),1-6, 6-2.
“I could have played three sets but I figured I should at least do 1,000 per cent right now. That’s what I tried to do,” Williams said. "It was good have a match like that.
"I definitely didn't think I would be in another final here ever. After the last final I had here (2001 when she lost and was booed), I never pictured myself being back. So it's interesting feeling."
Nadal was the champion at the event in 2007, 2009 and 2013, but has managed to win only one of the last 20 Masters events played; his last trophy at this level was in Madrid in May 2014.
The 29-year-old showed the form which has taken him to 27 Masters honours and which propelled him out of danger in the fourth round against German teenager Alexander Zverev, who missed a match point on a sloppy volley in their thriller.
The Serb was denied by Tsonga on two match points in the 10th game of the second set as the Frenchman held onto his serve for 5-all.
When the set went into a tiebreaker, Djokovic again came to the fore, converting on his third match-winner for the victory in just over two hours.
"Both sets were close, he was hitting some very big shots. I know it's always going to be tight against Jo. I'm just glad to be able to win."
Djokovic has won the last two Indian Wells editions and is bidding for a fifth trophy at the venue.
He leads the series with Nadal 24 wins to 23 for the Spaniard.
"Nadal is a completely different matchup against than any other player I've played here. He's a great competitor, a great fighter. He's been getting himself out of trouble a few times this week and showing why he's one of the best players in the history of the game.
"He never gives up. He always makes you play an extra shot. Always makes you earn the win. You know, I'm going into tomorrow's match knowing what's expecting me and I know how to get ready.
"I won the last couple times we played against each other, so maybe that can give me a slight mental advantage coming into the court."
Nadal said his turning point against Nishikori came as he trailed 1-3, 15-40 in the opening set, with the Asian ace a point away from a double break of serve.
But after rallying in that game to hold off disaster, a confident Nadal said:
"I feel myself strong mentally, feel myself with the right energy. When that happens, the rest is a little bit less difficult.
"I'm able to fight for every ball. I'm able to keep going during the whole match, believe in myself again, and that make me play with more energy, less nerves.
"That's so important for me, no? It's the way I play during all my career, and that give me a lot. And this week is being very, very positive for me. Very important."
Nadal, a 14-time grand slam champion, has not won a title of any kind since Hamburg on clay last July, one of three minor titles he lifted last season.
Victory in just over 90 minutes improved Nadal's record over Nishikori to 8-1, with Asia's top player beating Nadal in a Montreal quarter-final last August.
"This has been a very positive tournament, winning against great players. I had a tough draw and to be in the semi-finals, that's something very important for my confidence.
"Let's try my best tomorrow. Let's keep playing with the same energy. And we'll see what's going on."