Toro Rosso team boss Franz Tost has added to the congratulations flooding in for Daniel Ricciardo following confirmation of his move to Infiniti Red Bull Racing for 2014, but admits there is some disappointment at seeing the Australian leave.

A member of the Toro Rosso line-up for the past two seasons, Ricciardo has been tipped as the likely successor to compatriot Mark Webber for much of 2013, and Tost, while admitting that he would have chosen to retain the youngster's services, concedes that it is good that STR is fulfilling its role in the Red Bull development programme.

"Congratulations to Daniel, although we would have liked to keep him, because he is a talented driver who has done a great job with Scuderia Toro Rosso," the Austrian commented, "At the same time, we are very pleased to see him make this move, which means he will follow in the footsteps of Sebastian Vettel.

"When Dietrich Mateschitz acquired the team that became Toro Rosso, his stated aim was that it should be the final step in the training of young drivers, with the eventual goal of graduating to the 'senior' team. Daniel's move thus vindicates the work of the Red Bull Young Driver Programme and also proves that we at Toro Rosso have given him a good racing education."

Ricciardo's graduation will pair him with the last driver to make the move from Toro Rosso to Red Bull and, while neither the Australian nor Tost expects the task ahead to be an easy one, the transition will have been eased by a long relationship with the Milton Keynes team.

"Daniel already knows his new team, having tested for them a few times and I am sure he will soon feel at home there next year," Tost confirmed, "They won't even have to change the Australian flag on the side of his car!

With Ricciardo gone, attention will now switch to finding his replacement but, despite several names having been suggested, Tost insists that there will be no snap decision.

"As to who will replace Daniel at Toro Rosso in 2014, we will now look at all our options and make a decision at a later date," he confirmed, "There is no immediate need to rush."

World Series by Renault racewinner Antonio Felix da Costa is widely regarded as the favourite to partner Jean-Eric Vergne next season, although GP2 frontrunner Felipe Nasr has been mentioned as an alternative in recent weeks.