The Champions League winners had already put a temporary block on the forward's move until after Tuesday’s Uefa Super Cup clash with Sevilla in Tbilisi in a bid to ease Lionel Messi and Neymar into the action after their delayed summer holidays.
However, the Brazilian's bout of illness will keep him out for the next two weeks, prompting Barca to call for a further one-week hiatus before returning to the bargaining table.
But United, who have agreed to pay a fee rising to £22.3 million (€32m) for Pedro, are eager for the player to arrive sooner rather than later given that their Premier League campaign has already begun and they face a two-legged Champions League play-off with Club Brugge on August 18 and 26.
Pedro had shown an inclination to work at Barcelona’s pace after the club asked for the initial delay but an additional one-week block would rule him out of a further two United games, including the home leg of the Brugge tie.
Barcelona face Athletic Bilbao on August 14 and 17 in the two-legged Supercopa de Espana, and Pedro would again be a likely starter in Neymar’s absence should the 28-year-old agree to delay his exit again.
