a £100 million ($139m) deal at the Etihad Stadium seeing Jack Grealish break the British transfer record, while Romelu Lukaku may be heading back to Stamford Bridge for £98m ($136m).
United have also invested, with £73m ($101m) spent on Jadon Sancho and £34m ($47m) on Raphael Varane, but Keane believes more is required in order for the most prestigious of honours to be landed at Old Trafford.
Reflecting on recent recruitment business with ITV Sport, ex-United midfielder Keane has said: "Two very good signings, particularly Varane with his experience with the problem at the back. "Sancho, a young talented player who did well in Germany.
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