By Humeyra Pamuk

ANTALYA, Turkey (Reuters) - U.S. Secretary of State Marco Rubio said on Thursday the only way a breakthrough will happen in the efforts to end Russia's war in Ukraine would be through direct talks between President Donald Trump and Russian President Vladimir Putin, after Moscow sent a second-tier team to talks in Turkey.

Rubio, who spoke to reporters in Antalya, said he would travel to Istanbul for meetings on Friday with Turkey's Foreign Minister Hakan Fidan and a Ukrainian delegation, but said he did not have high expectations for the talks.

"I don't think we're going to have a breakthrough here until the president (Trump) and President Putin interact directly on this topic," Rubio said, echoing earlier comments from Trump.

The top U.S. diplomat described the current state of the talks to end the war as a "logjam," and said Trump was the only person who can break it.

Ukrainian President Volodymyr Zelenskiy had traveled to Turkey after Putin proposed talks there, before the Russian president decided against traveling to the talks himself.

Putin instead dispatched a second-tier team of aides and deputy ministers to Istanbul.

Rubio said the level of the officials sent by Russia was not indicative of a breakthrough, but said Trump was willing to stick with talks as long as it takes to achieve peace.

When asked if any efforts were under way to bring Trump and Putin together, Rubio said Trump was going to make decisions once his Middle East trip ends.

"Probably we'll wait until he finishes with his trip ... We'll wait to see what happens tomorrow, and then those decisions will be made about a timeline," he said.

(Reporting by Humeyra Pamuk; writing by Simon Lewis; editing by Chizu Nomiyama and Rod Nickel)