The Daily Mail Online's Sami Mokbel reports that the Gunners reopened talks Monday with Los Merengues, having initially failed to make any progress in their previous bid to sign Morata on loan.
An excerpt from Mokbel's report reads:
If the club cannot strike a short-term deal, they are prepared to spend heavily to land a reliable striker.
Colombia striker Martinez, 27, is a leading candidate, and he is thought to have a £33.2million release clause.
The pair present the North Londoners with two options at quite opposite ends of their careers. Morata is a budding 21-year-old only a few steps into his La Liga career, whereas Martinez is enjoying some of his most prolific form at the age of 27, and the Porto man could require significant investment.
Arsene Wenger's need for January additions to his forward line has become all the more necessary after Theo Walcott was ruled out for the rest of the season and is set to miss the World Cup, as per BBC Sport:
Though Morata holds vast potential, the Castilla academy graduate may not offer the impact Arsenal require as they head into the latter half of the season.
This is a player, after all, who has started just six La Liga games in his career, per Transfermarkt.co.uk, and would by no means be assured to start for the Gunners, offering little more than cover to Olivier Giroud.
Martinez, on the other hand, is experienced. He has already netted 12 goals in 14 Primeira Liga appearances this term. The South American is consistent, too, after he scored 26 goals during Porto's run to the Portuguese league title last season, per Transfermarkt.co.uk.
Martinez looks pinned on to feature for Colombia at this summer's World Cup, so he would be hoping for assurances over playing time if a move to the Premier League were to come about.
However, it helps that the forward was a fan of the North London outfit as a youth, quoted by Mirror Football's Ben Burrows as saying he "wouldn't hesitate" on making a move to the Emirates Stadium should the opportunity arise.
The Times' Matt Hughes has stated that Wenger is only seeking a short-term solution, with a big-money move preferred for the summer:
Neither attacker would be available to appear for Arsenal in the Champions League, having already featured in the tournament for their respective clubs.
However, for Wenger, the devil is very often in the details of any prospective transfer, and there's a substantial distance between his two top priorities this month.