The Spain international scored a hat-trick in la Roja’s hat-trick in 6-1 victory over 2014 World Cup finalists Argentina in the Spanish capital last week.
Isco played a key role in Real Madrid’s run to the Champions League final last term before he started in a 4-1 win over Juventus in the final at the Millennium Stadium.
However, the 25-year-old has found his first-team opportunities more limited this term, with Zinedine Zidane unable to procure top peformances from Isco.
The Spanish playmaker has been linked with a move to the Premier League in recent months amid uncertainty surrounding his long-term future at Real Madrid.
Isco appeared to publicly criticise his manager Zidane after Spain’s landslide win over Argentina to raise further questions about his prospects at Real Madrid.
The Sun’s chief football correspondent Ashton suggested that both Manchester clubs will be interested in Isco’s situation at Real Madrid, while Chelsea FC and Liverpool FC could also contend for his signature.
“When you question the coach’s credibility then you are reaching the end of the line very quickly,” Ashton told BBC Radio 5 Live.
“Of course we know about Manchester United’s continued interest in Isco. Those comments will continue to alert Manchester United. If you’re leaving Real Madrid, you’re leaving for Manchester City, Manchester United, Chelsea FC or at a push Liverpool FC.
“He has put himself in the shop window with comments like that.”
Isco has scored 39 times in 231 appearances in all competitions over the past five seasons at Real Madrid following a move from Malaga in 2013.
He has won one La Liga titles and three Champions League crowns during his career at Real Madrid so far.
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