Scotland boss Steve Clarke says the fight is on to make his 23-man squad for the Euro 2020 finals next summer.
Clarke brought 27 players into his camp for the triple-header of away games against Serbia, Slovakia and Israel.
That will have to be whittled down for next summer.
Aberdeen defender Andy Considine was in the squad and earned a third cap when starting in the 1-0 Nations League defeat to Slovakia on Sunday.
Considine has impressed in his three games since earning a debut cap last month for Scotland.
Injured players, such as former Aberdeen winger Ryan Fraser, will also return.
Clarke also knows players will move into contention between now and the summer.
The gauntlet has been laid down by Clarke – keep performing at club level and shine in the World Cup qualifiers in March to earn a spot in Scotland’s first major tournament in 23 years.
He said: “There will be a fight to be in the 23 next summer.
“That is what we want, that is the target for them. They are all going back to their clubs, but they’ll need to play well and stay fit and healthy.
“Of course we are thinking about the summer, but the next stage for them is these qualifiers in March.
“That’s the road I’m going down.”
Scotland experienced the euphoric highs and crushing lows of international football in a frantic six-day period.
Clarke’s side overcame Serbia in a Euro 2020 playoff final penalty shootout to secure qualification to a tournament for the first time since the 1998 World Cup.
Then they threw away a commanding four-point lead at the top of the Nations League by losing 1-0 to both Slovakia and Israel. That was enough for them to be overtaken by the Czech Republic who won the group.
Clarke insists all focus switches to the World Cup qualification campaign.
Scotland are in pot three for the December draw for Qatar 2022.
He said: “The playoff route via the Nations League has gone – we’ll just need to qualify from the group. That has got to be the aim.
“We are hoping for a nice draw.
“It’s a bit unusual to have qualifiers before then going to the Euros, but there’s no reason we can’t go in to these games with a lot of confidence and belief.”
Despite the disappointment of two successive Nations League defeats, Clarke is confident he has a squad desperate to improve.
Clarke will not meet up with the Scotland squad again until the World Cup qualifiers in March.
He said: “I don’t think we really appreciated the feeling back home (of sealing Euro qualification).
“Being such a long way away the whole time, we’d only get little snippets of it.
“But we know we achieved something big last Thursday.
“As a group of professionals we were disappointed we couldn’t give the nation another lift by getting the points we needed to be top of the Nations League section.
“There was small disappointment, but we have to remember this group of players have come a long way in just over a year.”
After the whirlwind of three away games in six days, Clarke will finally have time to reflect on the highs and lows.
He said: “It’s been a very intense few days. I’ll go home and probably sleep for three days.
“I’ll take the time to relax, reintroduce myself to my wife, children and grandchildren.
“I’ve not really had time to sit and analyse things. I am sure we will enjoy it in the coming weeks, maybe ask me again after the World Cup draw in December and I might have an answer by then.”