The draining physical effects of long flights and travelling through time zones is something many of us know all too well.

Mertens, 26, won the doubles title alongside Veronika Kudermetova in Fort Worth on Monday night.

Not even 24 hours later, after three flights and going through six time zones, she arrived in Scotland at 21:47 GMT on Tuesday night

She was not ready to play in the singles on Wednesday morning and, in her absence, Belgium lost both matches without their highest-ranked player as Slovakia clinched the best-of-three tie.

On Wednesday afternoon, Mertens won in the doubles alongside Kirsten Flipkens - which could prove important for the Belgians' hopes of reaching the semi-finals.

"I would be frustrated if I lost but we won, so this is all good," said Mertens, who is ranked 29th in the world.

"I had my flight at 10pm [from Fort Worth] and I was still doing media at 8:15pm.

"We rushed. I barely showered. We got to the airport at like 8:55pm. They said we had four minutes for the bags. One bag on the scale. Two minutes. Oh, my God.

"My mom and I ran to the gate and we made it. Then three flights, we went to Madrid, went to London, and then to Glasgow.

"It's been quite a journey."

The close proximity of the two tournaments has led to criticism, including from Poland's world number one Iga Swiatek.

Swiatek, the three-time Grand Slam champion, said the scheduling was "not safe" and withdrew from the BJK Cup Finals.

Mertens said she hoped the WTA and ITF would address the issue next year, but was able to look at the situation in "a positive way".

"I'm feeling good. It was a long trip, but I'm dedicated to play for Belgium," added Mertens, who had seven hours of sleep and a "little nap" before earning a 6-0 6-3 win with Flipkens.

"Even though we lost, we still have a chance. I think we have to look at on the positive side."