Manchester United star Ander Herrera has lamented the failure of both Radamel Falcao and Angel Di Maria at Old Trafford, but believes the South American duo made every effort to prove their worth. Louis van Gaal secured the services of the Colombian striker and the Argentinian star in the dying days of the transfer window last summer as his marquee signings to lead the Red Devils' attack.

Falcao arrived at the club on loan from Monaco following a lengthy period in the sidelines after suffering a knee injury but had previously garnered a reputation as one of the most clinical strikers in the world, both at Atletico Madrid and Porto. Di Maria, meanwhile, moved to Old Trafford for a club record £59.7m ($92.5m) deal after leading Real Madrid to the Champions League crown in the previous campaign.

However, the South American duo failed to replicate their best form during van Gaal's debut season in the Premier League. Hence the dutchman decided to part ways with both attackers earlier this summer - with Falcao securing another loan move from Monaco to Chelsea while Di Maria moved to Paris Saint Germain in a deal according to BBC, worth £44.3m ($68.8m).

Asked in an interview with Cadena Cope how such talented players failed to make an impression at Old Trafford, Herrera responded: "Because football is like that. There are some great players that don't work in specific places."

"I believe they made everything to prove their worth. They are two good professionals and two good friends that I will keep forever. Things don't went as we desired. Now they have started new experiences somewhere else and I wish them the best because they deserve it."

Herrera himself has also had his ups and downs during his time at United. The Spaniard ended last season in an impressive form but during the first-half of the campaign he struggled to convince van Gaal that he deserved a regular place in his line-up.

And the Spanish midfielder has once again seen his playing time limited in the new campaign following the acquisitions of Morgan Schneiderlin and Bastian Schweinsteiger. Herrera, nevertheless, proved his worth in the 4-0 Champions League victory over Club Brugge last Tuesday, scoring in his first start of the campaign.

"I am a team player. Should the manager want me to start I am happy but if not I will try to help the team too. I am very happy because the club is back where it deserves, in the Champions League," he replied when asked about his personal situation after the game against Brugge.

"The first goal last year was to return to the Champions League. We have already secured that and now we must think in fighting for everything. But we are aware that last year we were fourth [in the Premier League] and that we did not play European competition so we have to be cautious. We must go step by step. But we are Manchester United and our history demands us to fight for everything."