Celtic scouts were in attendance at Benfica's match against Belenenses this weekend.
The Bhoys have made an inauspicious start to the new campaign, and it may be that Ronny Deila is already thinking about making recruitments at the next available opportunity to bolster his squad.
In this piece we take a look at three Benfica players who Celtic may have had their eyes on...
Celtic's defence has been far off the requisite standard so far this season, and Deila may be thinking about introducing a new centre-back to his team.
If he is then Jardel would tick the box. The powerful defender started against Belenenses and put in a commanding performance, helping his side pick up a 6-0 victory.
Jardel has made 71 league appearances for Benfica across five years, meaning that he is by no means a guaranteed starter.
The winger has found first-team appearances hard to come by at Benfica, but he is still highly regarded.
A loan spell at Southampton did not work out for him last season, but he may fancy a move back to British shores and Celtic could do with an attacker of the Serbian's quality.
The Bhoys have struggled to inject a spark into their attack this term, and the addition of Djuricic could go some way to changing that.
Capable of playing anywhere down the left hand side, Eliseu would provide a good option for Celtic in two positions if they were able to complete a deal to bring him to Parkhead.
The rapid wide-man has been well travelled throughout his career, having played in the likes of Spain and Italy before moving to Portugal.
He may fancy a new test, too, and he would be an eye-catching coup for Celtic if they were able to snap him up.