Former Tottenham Hotspur forward Robbie Keane has called for the club to give boss Tim Sherwood time to make his mark at White Hart Lane.Sherwood, who replaced sacked head coach Andre Villas-Boas in December, is under pressure after falling behind in the race for a top-four finish in the Premier League.Despite having more than a year left on his contract, he is facing constant speculation about his future, with suggestions in some quarters that Dutchman Louis van Gaal will replace him this summer.Keane, who now plays for MLS side LA Galaxy, believes English football will never progress and find the best potential managers for the national team if young bosses keep getting the boot.He told Sky Sports News: “Tim is a great guy and I hope he gets the time to build a team that is his team.“If you want to get these young managers in to progress and eventually become manager of the national team, how can you get them in if you don’t give them opportunities?“Tim has been in the job for a few months and already there is talk of bringing in someone else to replace him.“I don’t know if that is coming from the club – I hope not and I would be surprised if it is – it is coming from somewhere because names of these different managers keep getting mentioned.”Read more Tottenham Hotspur transfer news.