Alonso in advanced talks over new Chelsea contract
Alonso has been linked with both Spanish giants after developing into one of Europe's strongest left-backs during his time at Stamford Bridge.
But the 27-year-old, who won his first Spain cap earlier this year, will not be following former Chelsea goalkeeper Thibaut Courtois to Madrid.
"What I can say is that I am very relaxed and happy at Chelsea," Alonso told AS.
"And the club must also be pleased with me because I still have two years left on the contract and they have offered me an extension. We are already in advanced talks about a renewal.
"If everything goes well, I think I will renew before the end of this month. In the coming days."
Official call-up for upcoming @SeFutbol matches:
11/10 Wales - Spain
15/10 Spain - England pic.twitter.com/LRgdKV6gkH
— Selección Española de Fútbol (@SeFutbol) October 4, 2018
Despite being included in the Spain squad for upcoming matches against Wales and England, Alonso is not taking his international place for granted and is willing to play out of position if required.
"I arrived for the first time for the friendly against Argentina, before the World Cup, and now I'm back with Luis Enrique," Alonso added. "But we all know that to be involved you need to maintain your best for your club to be in the coach's plans.
"What drives me now is to have some continuity, because this is now my second consecutive call-up. In addition to that, the games in September went well and were accompanied with good results. That also helps.
"I've always played as a left-back, except on some occasions in Italy for Fiorentina where they put me on the other side. But my natural fit is on the left. If I have to play on the right because the team needs it, I could do that. But, of course, it's not my place."
Spain take on Wales in a friendly on Friday before hosting England in the Nations League on Monday.