Hagi has agreed to play one more game for his country to bolster a three- man front line assembled by the coach, Victor Piturca, with the hope of beating their neighbours for the first time in 63 years.
Dinamo Bucharest's Florentin Petre, the Romanian league's leading scorer Ionel Ganea of Rapid Bucharest and the Valencia striker Adrian Ilie will lead the attack. "This match may not be a World Cup final, but it's important for our qualification," Piturca said.
Hagi, who has inspired Galatasaray to three Turkish titles in a row, was a key player in the national squad for 17 years before bowing out last year. He has never played alongside Ganea and Petre, both relative newcomers.
Romania's defence will be full of familiar international names, including Hagi's Galatasaray team-mate Gheorghe Popescu and Iulian Filipescu of Real Betis. But the Salamanca goalkeeper Bogdan Stelea remains doubtful three weeks after he suffered a muscle injury.
The Hungarians were unimpressed by Hagi's return. "We both have No 10 on our shirts." midfielder Bela Illes said. "I don't know who might be the best now. We'll see about that on the pitch."
The visitors are without their two best wingers. The Debrecen right winger Tibor Dombi is suspended, while Ujpesti's Attila Korso, who had been expected to start on the left, picked up an injury in training and will miss the game.
The Hungarian coach Bertalan Bicskei has welcomed the Porto striker Miklos Feher back into his squad and the 19-year-old is expected to play in the central attacking role with Jozsef Sebok on the right and Gabor Egressy on the left.
The match has generated strong passions, particularly in Bucharest, and 2,000 police police will be deployed around Steaua Stadium, although officials on both sides say that violence is unlikely. Police said the stadium would be sealed when 90 per cent of the seats were occupied and other fans, even latecomers with tickets, would have to watch the match on a screen at another ground.
The favourites Portugal lead the group with 12 points from five games, one point more than second-placed Romania. Hungary are level on eight points with Slovakia.
Barcelona's midfielder Luis Figo returns to the stadium where he launched his career at Sporting Lisbon for Portugal's meeting with Slovakia.
"This game will be very uplifting for me," Figo said ahead of his first game at the Jose Alvalade stadium since he moved abroad to join the Spanish champions in 1995.
Portugual's coach Humberto Coelho will return to a 4-4-2 system, with the midfielders Paulo Bento and Internazionale's Paulo Sousa providing cover for the defence.
Portugal have been in formidable goalscoring form in their two previous qualifying matches, beating Azerbaijan 7-0 and Liechtenstein 5-0 away.
"The match with Slovakia is one of the most important for us - it could be decisive," Coelho said. "The Slovaks have improved enormously since we beat them 3-0 in Bratislava. They are good defenders and are strong in counter-attack."
Slovakia's coach, Josef Adamec, said: "I hope our side will not make the same mistakes as when we played at home and lost 3-0, but I believe that this result will be better - perhaps a draw."