Lionel Messi
Lionel Messi scored his 200th goal for Barcelona on Wednesday. REUTERS

Fresh from securing qualification for the Champions League knock-out phase, Barcelona face a tough La Liga trip to Athletic Bilbao on Sunday.

The defending champions will be hoping to keep pace with league-leaders Real Madrid who are currently one-point clear of the Catalan club.

Barca forward Lionel Messi believes Real have improved upon last year, after spending over £50m on bringing Fabio Coentrao, Nuri Sahin, Raphael Varane and Hamit Altintop to the Bernabeu.

"Real Madrid have strengthened their team pretty well in the summer. They intended to do better than last term and have been doing just that," Messi told Marca. "They have grown a lot since August and are a better team than last season."

Messi scored his second consecutive hat-trick in Barca's mid-week Champions League win against Viktoria Plzen and the Argentine star reckons the European champions will only improve as the season progresses.

"We have also strengthened in the summer and have improved as well," he said. "It's fundamental that we get along as a team, to have a group of players that play this well isn't easy to find.

"We've known each other for years and we've always gotten along, this is why we've performed so well."

Barcelona remain unbeaten this season in all competitions but in-form Bilbao should present a tough test of their title ambitions, a fact Lionel Messi was quick to point out.

Athletic Bilbao probable XI: Iraizoz; Aurtenetxe, Toquero, San Jose, Iraola; Iturraspe, Javi Martinez, Susaeta, Ander Herrera, Iker Muniain; Fernando Llorente.

Barcelona probable XI: Victor; Abidal, Mascherano, Pique, Alves; Busquets, Hernandez, Iniesta; Fabregas, Villa, Messi.

Real Madrid Lionel Messi