Saudi Arabia opened their Group D challenge with a 2-1 defeat to Ivory Coast Under-23s, while Germany suffered a 4-2 loss to Brazil's Under-23s, with Richarlison scoring three times for Selecao.
Saudi Arabia recovered from a one-goal deficit to level the scores in the latter stages of the first half against Ivory Coast in their section opener in Yokohama on Thursday, with Salem Al-Dawsari on the scoresheet.
The Green Falcons were not able to pick up anything for their troubles, though, as a second-half strike from AC Milan's Franck Kessie allowed Ivory Coast to secure a vital three points.
There is now huge pressure on Saudi Arabia to pick up a positive result in this match, with only the top two from each group progressing to the quarter-final stage of the competition. As it stands, Saad Al-Shehri's team are third, ahead of Germany on goal difference but three points behind Brazil and Ivory Coast.
Saudi Arabia will finish their Group D challenge against Brazil on July 28, and Al-Shehri will know that anything other than a win against Germany is likely to end their hopes of progression.
The Green Falcons are competing in the Olympics for the first time since 1996, when they failed to make it out of the group stages, suffering three losses during a tough tournament.
Germany, as mentioned, are bottom of the section, having suffered a 4-2 loss to Brazil in their tournament opener in Yokohama on Wednesday night.
Nadiem Amiri and Ragnar Ache were on the scoresheet for the Germans, but Everton forward Richarlison scored a hat-trick for Brazil, while Paulinho scored a fourth for the South Americans in the final stages.
Germany were silver medallists at the 2016 Olympics, losing to Brazil in the final, but they actually did not compete in the competition between 1992 and 2012.
Head coach Stefan Kuntz was restricted in terms of the players that he could select for this tournament, but there is still plenty of quality in the squad, with captain Maximilian Arnold and experienced attacker Max Kruse arguably the standout names.
Germany will fancy their chances of picking up a positive result on Sunday, which should leave them in a strong position to reach the quarter-finals heading into their final Group D clash with Ivory Coast on July 28.
Saudi Arabia did not pick up any injury problems during their defeat to Ivory Coast, while head coach Al-Shehri has no suspension issues despite two players picking up bookings on Thursday.
It would not be a surprise to see the same XI sent onto the field for the second successive match, as Saudi Arabia certainly had their moments against Ivory Coast during an impressive performance.
Germany will be without the services of captain Arnold on Sunday, as the midfielder received a red card in the second half of the defeat to Brazil on Thursday.
As a result, there could be a spot in the middle of the park for Ache, who was on the scoresheet against Brazil, while Arne Maier is also likely to retain his spot.
Head coach Kuntz decided to change one of his centre-backs at the interval on Thursday, and Jordan Torunarigha could now come in for a start in the middle of the defence.
Kuntz is likely to resist the temptation to make wholesale alterations, though, with Kruse again set to be joined by Amiri and Marco Richter in the final third of the field.
Saudi Arabia Under-23s possible starting lineup:
Al Yami; Abdul Hamid, Al-Amri, Al-Hindi, Al-Shahrani; Al-Hassan, Al-Faraj; Yahya, Al-Najei, Al-Dawsari; Al-Hamdan
Germany Under-23s possible starting lineup:
Muller; Henrichs, Torunarigha, Uduokhai, Raum; Maier, Stach, Ache; Amiri, Kruse, Richter
We say: Saudi Arabia Under-23s 0-2 Germany Under-23s
This is a potentially very tricky match for Germany, who are under pressure to pick up a positive result. Saudi Arabia will be competitive on Sunday, but we are finding it difficult to back against the Germans, ultimately settling on a two-goal win for Kuntz's side.
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