Viktor Gyokeres is about to cost Arsenal millions - and could force immediate payout vs Chelsea

Arsenal paid £55million for Viktor Gyokeres last summer, but the deal they agreed with Sporting included almost £9million in add-ons to take the total fee paid towards £64million

Viktor Gyokeres could earn Sporting over £400,000 this weekend if the Arsenal striker scores or assists three goals against Chelsea.

As part of the add-ons agreed when signing the Sweden international last summer, his former club are due £437,000 for every 20-goal contribution, according to The Sun. After scoring twice against Tottenham Hotspur in the north London Derby, Gyokeres is up to 15 goals and two assists across all competitions.

A hat-trick at Emirates Stadium on Sunday would bring up the milestone, although it would take an unprecedented performance. The most goals Gyokeres has contributed in a single match this season are two.

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He has, however, done so six times this term, one of which was against Chelsea in the League Cup semi-final first leg. Gyokeres scored Arsenal's second and set up Martin Zubimendi for their third in the 3-2 away win.

That was the first match he scored in and assisted a teammate's goal. The only other occasion came a fortnight later, during another 3-2 win, this time against Kairat in their final match of the Champions League's league phase.

Sunday's win over Spurs was his fourth brace, with the others coming against Atletico Madrid, Leeds United and Sunderland. Gyokeres' goals, however, will cost Arsenal no more than £874,000 extra, as there is only one more payout related to his scoring if the striker manages to hit 40 goals and assists.

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Appearances, though, are an aspect Arsenal have already had to top up the initial fee they paid Sporting. They handed over £1.1million after Gyokeres made his 20th outing that lasted at least a full half - 45 minutes - which was the 3-2 win over Bournemouth.

The Portuguese club will continue to receive that amount after every 20 appearances that meet the minutes-based criteria, up to No. 80. At that point, they will have earned £4.4million in total from their former striker playing for Arsenal.

Gyokeres is up to 30 after the north London Derby, so another outlay could come before the end of this season if he stays fit and in form. At this rate, the Gunners are due to pay up on that front next season fully.

Sporting will also be preparing for the £874,000 they are due from the Gunners upon qualification for next season's Champions League. They are due to receive that amount each time Arsenal qualify, until it reaches £3.5million, for a total of four payouts.

Come the season's end, Gyokeres could cost Arsenal a total of £3.5m in add-ons, including the clauses he's already triggered.