The 17-year-old is one of Sporting’s top prospects and Arsenal are eager to sign him ahead of other European clubs.
Their initial €20m offer was rejected by Sporting and they improved on that significantly with a €32m bid.
But even that wasn’t enough for Sporting, who are determined not to let Joelson go for less than his €45m release clause.
The Gunners may return this week with a third bid, conscious that more clubs are interested in the winger.
Neither club has made an offer yet, but at any time could threaten Arsenal’s pursuit of Joelson.
New meetings are scheduled this week with the serious possibility that Arsenal may meet Sporting’s €45m asking price.