Fischer found the net for Denmark in their friendly match against Liechtenstein on Wednesday evening.
Fischer's goal - a smart finish from close range - was the fourth in a 5-0 victory for the Danes, and his fourth goal as a full international.
Denmark begin their World Cup qualification with a home tie against Armenia on Saturday.
Gaston Ramirez and Cristhian Stuani
Ramirez was unable to prevent Uruguay's defeat to 10-man Argentina in World Cup qualification.
The playmaker was a 70th minute substitute for the away side, who fell to a goal from Lionel Messi following the Barcelona man's international retirement U-turn.
Cristhian Stuani was an unused substitute in the match.
The Boro duo will hope for a more positive result when Uruguay continue their qualifying campaign against Paraguay in Montevideo next Wednesday.
Aynsley Pears and Hayden Coulson
Goalkeeper Pears represented his country for the first time as England Under-19s drew 1-1 with the Netherlands.
Everton midfielder Tom Davies gave England the lead just before the interval, only for Justin Hoogma to equalise six minutes from time.
Pears played the second half, and the penalty shootout following the game, which England won 9-8.
Defender Coulson was an unused substitute.
England's U19s play again on Sunday, against Belgium in Brussels, as they prepare for Euros qualifying in October.
Dael Fry and Harry Chapman
Less than 24 hours after signing a new 5-year contract at Boro and agreeing a loan deal with Rotherham United, Fry played 90 minutes for England Under-20s in a behind-closed-doors friendly against Brazil.
New England boss Sam Allardyce was watching as the U20s earned a 1-1 draw with their South American opponents, Brazil forward Richarlison opening the scoring before Ainsley Maitland-Niles levelled for the hosts.
With honours even at full time, the two sides agreed to a penalty shootout, which was won 4-3 by Brazil.
England don't have to wait long for a chance at a reprisal - the teams meet for another friendly this Sunday.
Chapman, currently on loan at Sheffield United, was a late addition to Aidy Boothroyd's squad, and did not feature in this game.
Elsewhere, Brad Guzan and the USA begin their World Cup qualification on Friday with an away tie to St Vincent and the Grenadines, followed by a match against current group leaders Trinidad and Tobago in Florida on Wednesday.
After finalising his loan move to Boro from Arsenal on Tuesday, Calum Chambers linked up with Gareth Southgate's England Under-21 squad. The Three Lions face Norway on Tuesday, knowing that a victory would strengthen their position at the top of their Euro qualifying group with just two games remaining.
Emilio Nsue's Equatorial Guinea side will be looking to revive their fortunes at the foot of Group C when they play host to closest rivals South Sudan on Sunday, while Julien de Sart is with Belgium Under-21s for their European Championship qualifiers against Malta and Czech Republic, which take place on Friday and Tuesday respectively.