John Toshack says Ryan Giggs' lack of managerial experience is a legitimate concern for supporters underwhelmed by his start as Wales boss.
But Toshack, who managed Wales between 2004 and 2010, has urged fans to back Giggs when the 2020 European Championship qualifiers start in March.
Giggs' only previous experience in the managerial hot-seat before taking charge of Wales was a four-game caretaker spell at Manchester United in 2014.
His first year as Wales manager ended on a sour note this week as the Dragons missed out on promotion to the top tier of the Nations League and then lost a friendly 1-0 to Albania, who are a lowly 60th on FIFA's world rankings table.
Giggs' record now reads won three, drawn one and lost five – ironically the identical record Toshack had from his opening nine games as Wales manager.
"The thing is we've no guide on what Ryan's done to know the type of manager he is or what his thinking is going to be," Toshack told Press Association Sport.
"There is no reference point on Ryan in football management. We can't say 'he did really well there' or 'he didn't do well there'.
"We just don't know – and Welsh fans have rightly got concerns.
"But the decision has been made that he was the best candidate for the job, and everybody has to get behind him and support him as best as we can."
During his six-year reign, Toshack blooded many of the players that would go on to help Wales end their 58-year wait to qualify for a major tournament and then reach the semi-finals of Euro 2016.
Giggs has embarked on a similar youth promotion policy and handed 10 players their international debuts.
Others like Ethan Ampadu and David Brooks have also been given further opportunities after winning only a couple of caps under previous manager Chris Coleman.
"It's easy to criticise, but I think Ryan has maybe got a similar job to when I went in," Toshack said.
"He's gone in and thought 'Hey, the average age of this team is high. We've got to start getting young lads in and move this around a little bit'.
"The advantage he's got is that a lot of them are playing in the Premier League.
"The players who made their debuts under me are all queuing up for 100 caps now. But he's got a similar job to me in the next six to 12 months.
"You need to mix these younger players in and give them a chance at international level, but you need a few of the older ones in there with them.
"You need good types to be able to introduce the younger ones in the right way to international football and help them make the grade."
Wales have scored 13 goals under Giggs, but 10 of those came in two handsome wins against China and the Republic of Ireland.
The 44-year-old has been criticised for naive tactics as he has struggled to find a balance between defence and attack, been too open at the back at times and failed to get the best out of star pair Gareth Bale and Aaron Ramsey.
"Look at Ryan's career and the team and manager (Sir Alex Ferguson) that he played for," Toshack said.
"It's very positive that he takes that idea of management in with him, I was the same having played for Liverpool and managed Real Madrid.
"You want to do the same kind of thing with Wales, but sometimes you start to think 'I've got to box a bit clever here'.
"If you go to Germany and are missing five players, you've got to think differently.
"Ryan will know the game inside-out with what he saw with Fergie, but whether he can implant those things and his own ideas into it is another thing."
:: John Toshack was speaking at the book launch of 'Toshack's Way: My Journey Through Football', which is published by deCoubertin Books and costs £20.
