'I've played well the whole time in the States this year,' he said. 'Today conditions were very tough.'

Federer's win took the record of the double Cincinnati champion to 44-7 on the season.

'This win today was perfect,' said Federer. 'It gives me another opportunity to play another match. I'm further into the tournament, which then normally makes me play better. I'm excited about tomorrow.'

The pair took to the hard court in hot, windy conditions after morning rainstorms, with Ferrer getting the early jump on the world number one.

Federer's 8-0 record in the series counted for little in the first set, with Ferrer recovering from an opening-set break and re-breaking the Swiss superstar for 5-3.

The Spaniard closed out the set as Federer produced 16 unforced errors, a display that was quickly corrected as the top seed won the second set to level and recovered from a break down with an immediate break-back in the third before finally advancing on the first of three match points.