Francis Tiafoe enjoyed an important Laver Cup victory over Daniil Medvedev on Saturday, with the American thriving on confidence after feeling "like Roger Federer".

American Tiafoe rallied past Team Europe's Medvedev 3-6 6-4 10-5 to send Team World into a 4-2 lead, at least temporarily.

Carlos Alcaraz soon levelled the team series in Berlin with an impressive 6-4 6-4 victory over Tiafoe's fellow American Ben Shelton.

Swiss great Federer was in the crowd to watch Tiafoe's performance, much to the delight of the 26-year-old.

"Honestly I just started having fun. Laughing with my team, laughing with my team over there and here. Just having a bit of fun and started really finding my rhythm," Tiafoe said.

"The courts are obviously much slower than I'm used to playing on, so it's tough playing Daniil on this court. But after the second set, midway into the second and in the tie-break, I felt like I was Roger Federer, honestly."

Tiafoe had lost all five previous ATP Tour meetings with Medvedev but continued his fine form after reaching the US Open semi-finals for the first time, along with making the final in Cincinnati.

"I just have a lot more confidence in myself. I'm having a lot of fun playing the game at the moment," Tiafoe added. 

"I'm just trying to play the right way and compete as hard as I can, let the chips fall where they may. I respect everyone, but I'm just not fearing anyone at the moment.

"I'm just going out there, taking it to guys and seeing what happens."

Alcaraz fell on his Laver Cup debut in the doubles alongside Alexander Zverev but responded with a near-perfect singles performance against Shelton.

"I'm really happy to be part of Team Europe in the Laver Cup for the first time," Alcaraz said after his first win in the competition.

"I'm trying to be as [good] a partner as I can, as [good] a player as I can to help my team. I played against Ben, a really powerful player, a really tough one.

"I'm pretty happy because I played a really solid match from the beginning until the end of the match."

Taylor Fritz subsequently restored Team World's lead with a 6-4 7-5 victory over Germany's Zverev, before doubles success followed for Shelton and Alejandro Tabilo.

The Team World pair dispatched Casper Ruud and Stefanos Tsitsipas 6-1 6-2, securing a 8-4 lead for their side heading into the third day of action.