LONDON—Top 5 players don’t often supply stress relief to opponents.

Jack Sock is hoping that’s the case at this week’s World Tour Finals.

Watch: Sock Befuddles Federer

Sock, who fell to Roger Federer, 6-4, 7-6 (4), in today’s World Tour Finals opener, says the six-time tournament champion’s presence poses pressure.

The eighth-seeded American is optimistic that stress will subside a bit in his upcoming round-robin matches against third-ranked Alexander Zverev and fifth-ranked Marin Cilic, who square off tonight.

“It will be different for sure,” Sock said of his remaining round-robin matches. “Roger puts a pressure on you that I feel no other player really does. I'll definitely be able to maybe hit my way into the next few matches, have some longer rallies, not feel sort of the presence he puts on you when you're out there.”

The 25-year-old Sock did not face a Top 15-ranked player en route to the Paris Masters championship, including his three-set comeback against 77th-ranked Serbian qualifier Filip Krajinovic in the final.

Sock is hoping past success will be empowering in London.

Sock is 2-0 lifetime vs. 2014 US Open champion Cilic and has split two meetings with Montreal champion Zverev. The 2014 Wimbledon doubles champion and an Olympic gold-medal champion in mixed doubles and bronze medalist in doubles, is more comfortable closing at net than Zverev or Cilic.

“Yeah, I've had wins against both of the guys,” Sock said. “Had losses, as well. But at least I can take stuff away from those matches where I've had the wins and apply it for the rest of the week.”

Photo credit: Rolex Paris Masters