ARSENAL have emerged as Middlesbrough’s leading rival for the signature of Borussia Dortmund centre-half Neven Subotic.

Subotic has been to the Riverside for talks after Boro tabled a bid of around £12m for the 27-year-old defender, who has spent the last eight seasons at Dortmund.

However, they have been unable to complete a swift deal and Arsenal have now made a formal approach of their own to Dortmund officials.

Arsene Wenger is willing to match Boro’s bid for the Serbia international, and the Gunners boss is hoping to hold talks with Subotic and his representatives this weekend.

Boro officials had been optimistic about their prospects of landing the defender, who claimed the Bundesliga title in successive seasons in 2011 and 2012.

Arsenal’s interest has complicated matters though, and while Subotic’s chances of regular first-team football would be greater at the Riverside than the Emirates, the lure of more Champions League action could persuade him to shun Boro’s advances.

Liverpool have also been linked with a possible approach, along with German side Koln, and Subotic’s future should become clearer next week.

Middlesbrough have made five signings already this summer, but only two are likely to be involved in tomorrow’s opening pre-season friendly at York City.

Marten de Roon and Jordan McGhee should both feature at Bootham Crescent, but Bernardo Espinosa is unavailable because of injury and Viktor Fischer only joined up with his new team-mates on the training ground for the first time yesterday so is not expected to feature tomorrow.

Victor Valdes is still to take part in a full training session since signing a two-year deal with the Teessiders, and is unlikely to be involved in tomorrow’s lunch-time kick-off.

Aitor Karanka will name a completely different side in each half in a game that will witness Alex Baptiste’s first appearance in a Middlesbrough shirt since he broke his leg at the same venue in a pre-season game 12 months ago.

Boro face York and Doncaster before leaving for a training camp in Marbella that will feature a friendly against La Liga side Real Betis on Tuesday, July 19. A further two games should be confirmed shortly.

Fischer will be involved in the games in Spain, and having joined up with the rest of the Boro squad following an extended break because of his international duties at the start of the summer, the winger, who graduated from Ajax’s prestigious academy, is determined to take his career to the next level.

“What you get from Ajax is a great education,” said Fischer. “I hope that I can show that when you go abroad to England and the Premier League, you can still improve and get even better.”

Boro kick off the new campaign with a home game against Stoke City on August 13, and Fischer has already identified the matches against Tottenham and Leicester as key moments in the season.

“There are so many big matches, that’s one of the reasons you come here,” said the Denmark international. “We all know the big clubs – Chelsea, (Manchester) United, Liverpool, Arsenal – those are all really big games.

“For me, the game against Tottenham and Christian Eriksen, a really good friend of mine, is going to be really exciting. Kasper Schmeichel at Leicester is also going to be nice.”