18-year-old Zhou Yi came back to beat Matic Kriznik to lift China to a 3-2 victory over Slovenia on Saturday, to reach the Davis Cup World Group II finals.
Zhou fired nine aces and converted six break points to beat Kriznik 5-7, 6-1, 6-3 in one hour and 58 minutes.
"It was a match full of tension and pressure for me. I am very happy to win the match for me and for the country," Zhou said.
China had held a 2-0 lead after Zhang Zhizhen eased past Matic Kriznik and Zhou overcame Sebastian Dominko on Friday.
However, in Saturday's matches, Blaz Rola and Grega Zemljia beat Zhang and Bu Yunchaokete 6-3, 6-4 in the doubles before Dominko upset Zhang 6-3, 6-4 to help Slovenia pull level.
"I believe this match is a breakthrough for me, because I managed to keep calm and find a way to win in such a crucial moment," Zhou added.