Daniil Medvedev fired Russia into the final of the ATP Cup on Saturday with a tense 3-6, 6-3, 7-5 win over an injury-hampered Alexander Zverev after the German destroyed a racket in frustration over a lost service break.
Russia will meet Italy in Sunday's final after Matteo Berrettini sealed a 2-0 win against Spain by beating Roberto Bautista Agut 6-3, 7-5.
Zverev had treatment on a lower back injury in the second set against Medvedev and slammed his racket into the court after slapping a wild second serve into the tramlines to be broken at 5-5 in the deciding set.
In a madcap finish, Medvedev double-faulted twice on match-point and saved five break-points before finally wrapping up proceedings with a fierce forehand down the line that Zverev could only push long.
"It was strange," said world number four Medvedev after sealing the tie 2-0 for Russia.
"Crazy match, happy to win, even if many things I didn't like."
Nursing a sore back, world number two Rafael Nadal sat out of another match for Spain.
His team mate Pablo Carreno Busta lost 6-2, 1-6, 6-4 to Fabio Fognini in the earlier match.
Andrey Rublev got Russia off to a bright start with a 3-6, 6-1, 6-2 win over Jan-Lennard Struff.
Serena shrugs off shoulder issue, 'relaxed' about Slam record bid
Serena Williams is "super confident" her injured shoulder will hold up for the Australian Open and says she feels more relaxed about the "burden" of bidding for a record-equalling 24th Grand Slam title.
Williams, a seven-times champion at Melbourne Park, pulled out of the warm-up Yarra Valley Classic on Friday, robbing the tournament of a marquee semi-final with world number one and home hero Ash Barty.
The American great said she would have to manage her shoulder through the Australian Open but was feeling "pretty good".
"I've gotten a lot of treatment already on my shoulder," Williams told reporters at Melbourne Park on Saturday.
"But I'm super confident it's going to be great. I'm feeling very confident, I think is a better word, and getting ready for hopefully the next two weeks."
Williams, who opens her tournament against unseeded German Laura Siegemund, won the last of her 23 Grand Slam titles four years ago at Melbourne Park when in the early stages of pregnancy.
Despite making four Grand Slam finals since motherhood, the 39-year-old remains one short of Margaret Court's all-time record.
"It's definitely on my shoulders and on my mind," she said of the record.
"I think it's good to be on my mind. I think it's a different burden, I should say, on my shoulders because I'm used to it now. It's more relaxing I would like to say, yeah."
Williams has beaten 51st-ranked Siegemund in both their previous matches, including the quarter-finals of last year's Auckland Classic in the leadup to the 2020 Australian Open.
"She has a different game," said Williams.
"She mixes up the pace a lot. It will be a really good match for me to get in there early and play my best."