The 16-year-old Leicester City winger had been strongly linked with a move to Arsenal and looked destined to complete a switch to the Emirates Stadium.
However, Arsenal have so far fallen short of Leicester's £10m valuation of the youngster, and that hold-up has created an opening for a rival to move in.
Manchester City have taken advantage of the situation to make their own pitch for Monga, stepping up their interest as Arsenal's negotiations stall.
Monga is well known to City's manager coach Enzo Maresca from the Italian's time in charge at Leicester, says the Daily Mail.
Maresca is said to be ready to welcome the teenager into the City set-up, viewing him as a player capable of adding competition further up the pitch.
The winger has already committed his immediate future to Leicester, agreeing a one-year scholarship contract at the King Power Stadium.
That scholarship deal is set to convert automatically into a full professional contract once Monga turns 17 next week, on 10 July.
His age means any transfer this summer would be subject to strict regulations governing the movement of young players between English clubs, with compensation likely to form part of any deal.
Arsenal's interest in Monga has been public knowledge for some time, and the Gunners had appeared to be in pole position to land him.
Manchester United and Brentford have also shown interest in the winger over recent months, underlining the level of competition for his signature.
With City now firmly in the picture, Arsenal face a battle to close out a deal they had long considered close to completion.
The next fortnight is likely to prove decisive, with Monga's professional status set to be confirmed at Leicester regardless of which club ultimately wins the race for him.