Wales manager John Toshack says the strike partnership of Paul Parry and Freddie Eastwood is "not quite right".
"Without Craig Bellamy, for us to play with two front men is a luxury," said Toshack, after Parry returned from Wales exile in the 2-1 loss to Georgia.
"A lot of the problems we had were behind Parry and Eastwood and in front of Carl Fletcher and Carl Robinson."
Parry said: "We have to get used to each other, maybe I can partner Freddie again in the World Cup qualifiers."
606: DEBATE
"It was nice to be back for Wales, but obviously the result and the way we performed in the second half was disappointing," said Parry, who had kept himself off the international scene for personal reasons as he went through a difficult divorce.
"I'm coming back and have to learn, we need to put the loss to the back of our minds and concentrate on the World Cup qualifiers, starting at home to Azerbaijan on 6 September."
Parry joined Cardiff from then non-league side Hereford in 2004 and rapidly progressed to international level.
His return to the fold with his 12th cap offers Wales a valuable striking option with Craig Bellamy's ongoing injury problems.
"The Georgia defeat was very disappointing, but it was a very timely reminder that every game is difficult"
The U21s now face the Romanians away on 9 September - a day before the senior side play a World Cup qualifier in Russia - and probably need a victory to make the play-offs.
Toshack has said that Wayne Hennessey, Chris Gunter, Gareth Bale, Dave Edwards and Joe Ledley should rejoin the senior squad, while others like strikers Sam Vokes and Ched Evans could also come into contention.
"The manager had his reasons for dropping players to the U21s," Wales captain Simon Davies told BBC Sport Wales.
"I'm sure that they'll be back with us in a couple of weeks and we'll be stronger for that.
"The Georgia defeat was very disappointing, but it was a very timely reminder that every game is difficult.
"As long as we can learn from that it will hopefully help our concentration against Azerbaijan."