Chelsea had explored the possibility of adding the experienced free-agent midfielder to their squad, but Alonso opted to trust the options already available to him rather than bring in the 29-year-old Portuguese international, according to Fussballtransfers.
Sanches, who has been a free agent since terminating his contract with Paris Saint-Germain on deadline day, has reportedly attracted interest from clubs across Europe's top five leagues, with Sevilla among those credited with monitoring his situation.
He left OSC Lille for PSG in 2022 but never established himself in the French capital, making just 27 appearances in four years and spending three successive seasons out on loan at Roma, Benfica and Panathinaikos without earning a permanent move at any of them. His time in Paris was also disrupted by fitness problems, with more than 20 recorded injuries costing him well over 500 days on the sidelined across his four years at the club.
Alonso and Sanches were team-mates during their time together at Bayern Munich, where the Portuguese once looked destined for the top after winning the Golden Boy award at 19 and helping Portugal lift the European Championship in 2016.
His career revival instead came at Lille, who signed him for around €20 million in 2019 and where he won the Ligue 1 title in 2021 before his move to PSG a year later.
Chelsea's midfield options have come under scrutiny following the £125 million departure of Enzo Fernández to Manchester City on deadline day, a sale that was not followed by a replacement after moves for Monaco's Lamine Camara and Roma's Manu Koné both collapsed late in the window.
Reece James and Malo Gusto were both used in central midfield during Sunday's 2-1 defeat to Arsenal, with Moises Caicedo and Jordan Henderson both sidelined, and Alonso insisting afterwards that his existing squad has "several options" and simply needs to find the right balance. Chelsea had also made contact over a possible move for free agent Georginio Wijnaldum before he opted to join Saudi club Al-Ittihad instead.