Middlesbrough v Millers preview: It's been a bit emotional for Kyle Vassell

Manager Warne went against his better judgement last weekend by selecting Vassell to face Bolton Wanderers even though he suspected his forward had been affected by his first ever call-up by Northern Ireland.

The 25-year-old gave a below-par display against the Trotters, but the boss is confident his player will be back to his usual self when the 20th-placed Millers travel to Championship leaders Middlesbrough this evening.

"He's been away with Northern Ireland for the first time and I think the emotional excitement of that takes it out of you," Warne said.

"The pride he felt playing for his country, then travelling back, training for a day and then playing the day after, it took its toll, if that makes sense.

Vassell made his debut for Michael O'Neill's side during the international break, appearing as a substitute in a 1-0 Nations League defeat in Austria before being an unused sub in a 2-0 loss in Bosnia-Herzegovina in the same competition.

"Looking back, maybe I made an error starting him," Warne said. "I should have probably gone with my gut feeling more and thought he might struggle. But he's been one of our key players, especially at home. I like having his pace and power in the team.

"I thought it was emotional tiredness. I don't think it was a physical thing because he's a fit as a flea.

Boro beat Sheffield Wednesday 2-1 at Hillsborough last Friday, a day before Rotherham drew 1-1 at home to Bolton, yet Warne shrugged off the fact Tony Pulis's side have had longer to prepare for the contest at the Riverside Stadium.

Millers manager Paul Warne

"I would love us to have had the extra day, but I think our lads will have recovered in time," he said. "It's better, say, than playing Boro on Wednesday night and then going to Preston on Saturday. I would have more of an issue with that.

"Boro will have had more rest, obviously, but sometimes your body can go into 'sleep' mode when you have an extra day. Being sincere, I'm not too concerned."

Boro top the table and Warne is under no illusions about the side of the task facing his team who are still searching for their first away point since winning promotion last season.

"I approach the challenge of Boro with a smile on my face and a skip in my step," the Millers boss said. "We approach all our games the same. Middlebrough are doing really well, top of the league. They invested really well in the summer.

"We have to have a bit of composure on the ball when we have it. Every game away from home for us is difficult. Every Championship is difficult. But if we play as well as we can do and have that bit of luck, then who knows?"