"Ryan looks in great form, and is strolling about like he is (Real Madrid legend Alfredo) di Stefano telling everyone what to do, and he scored a fine goal in Amsterdam (for Man Utd) last Saturday).
"But I am a little concerned about the problem with Wayne Rooney and Paul Scholes (both sent off against Porto on Friday) and whether they will start the season.
"There's also the situation with Gary Neville and Rio Ferdinand not being completely fit.
"Maybe a friendly with Bulgaria four days before the season starts for Ryan, when it looks like United will be without Michael Carrick, could be a problem for us.
"It might well be that Manchester United's problems are a concern. It is not about club versus country, it is about being sensible.
"I know what it is like for managers, you want players to avoid injuries just before the season starts."
Toshack would like Giggs to be around the squad in Cardiff next week, but will not criticise the 32-year-old should he not appear.
The manager said: "Ryan has played in eight of the 12 games for me, two friendlies and in six competitive games.
"We understand the situation, it is not about having players pulled out, we will look at what is in the best interests of all of us.
"I would expect Ryan to be with us, since he has been captain he has been excellent. His presence and performances he has scored four in his last four games has been very positive for us.
"His attitude and everything about him has been really first class. But it is a very delicate time of the season."