The Reds are getting their season back on track with four wins on the trot after losing two of their opening three Premier League games, the same number of defeats they suffered throughout the whole of last season.
Liverpool's Spaniard-heavy squad looked disorientated in their early fixtures as defeats to Tottenham and Aston Villa threatened to de-rail their title bid almost immediately.
In the summer, Spain played five matches en-route to their third-place finish in the Confederations Cup in the summer, meaning a grueling pre-season regime for those involved.
With key players Fernando Torres, Pepe Reina and Riera himself a part of the Spain set-up, the winger believes the competition may have effected Liverpool's early performances.
"The pre-season was hard and sometimes you start the season in not the best condition and maybe we have had that this year with Liverpool," Riera told The People.
"But now things are becoming better and we have more confidence now.
"It could have been the Confederations Cup or it could have been because you have to work really hard in pre-season so the first games then won't be the best because you don't feel at 100 per cent.
"But the most important thing is the present and we are feeling really confident and things are coming like last year."
Liverpool are hoping to end a 20-year title drought this season and overtake rivals Manchester United in the record number of titles won after the Red Devils equaled their haul of 18 last season.
"We know we have to win the Premier League, definitely, and fans are behind that a lot," added Riera.
"But we want to fight for everything, not just the Premier League. We want to win everything."