Crystal Palace are in discussions with free agent Takehiro Tomiyasu over a permanent deal, with the former Arsenal defender already training at the club and named among the substitutes in Tuesday's pre-season friendly against Lens.

The 27-year-old Japan international is understood to have reached a broad agreement on personal terms with Palace, though head coach Pierre Sage must still sanction the signing. Should Sage proceed, Tomiyasu is seen as a candidate to fill the left-side role in a back three the manager plans to deploy next season.

Fitness the key hurdle

Palace remain confident in Tomiyasu's quality, but the club are exercising caution over his fitness after a period severely disrupted by knee problems. After leaving Arsenal by mutual consent last season, Tomiyasu joined Ajax, making eight appearances for the Dutch club before the end of the campaign.

Defensive rebuild under way

The potential addition of Tomiyasu forms part of a wider effort by Palace to reinforce their backline this summer. First-choice central defender Maxence Lacroix is set to depart for Chelsea, leaving a significant gap to fill.

Palace have already submitted at least one offer for Augsburg centre-back Chrislain Matsima, with negotiations between the two clubs ongoing over a deal reported to be worth around 30 million euros (£25.7 million). The Eagles are also monitoring a possible loan move for Chelsea's 20-year-old defender Josh Acheampong, although Chelsea have yet to signal any willingness to let him leave Stamford Bridge.

BBC Sport reported last week that Palace hold a strong interest in Brest centre-back Raphael le Guen, adding another name to an increasingly active summer pursuit of defensive reinforcements.