Antonio Conte said his Tottenham Hotspur squad lacks the depth to challenge for both the Premier League and Champions League titles.
Conte was unable to call on the injured forwards Richarlison and Dejan Kulusevski for Sunday's 2-1 defeat by Newcastle, while Cristian Romero and Pierre-Emerick Hojbjerg were left out of the squad due to fatigue.
Spurs host Sporting in the Champions League on Wednesday before taking on Bournemouth in the Premier League on Saturday.
"My only worry in this moment is that we have to try to keep the fingers crossed that we don't have injuries because we are not a team with a squad depth to face competition like Premier League and Champions League," Conte told reporters.
"But this is not something against the club, we knew this situation."
Conte guided Spurs to a fourth-place finish last season after taking over from Nuno Espirito Santo last November.
But Tottenham's best start to a top-flight season since the 1963/64 campaign has now had a harsh reality check with back-to-back defeats. They stay third with 23 points from 12 games, and are seven games into a run of 13 matches in 43 days.
Conte warned it will take a few transfer windows for him to assemble a squad capable of challenging for major honours.
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"I spoke with the club at the start of the season, I said 'We have to go step by step, time and patience to have two, three transfer markets to bring this squad [to be] competitive to play two important competitions ...'
"This situation makes me frustrated because I'd like to play these type of games and the Champions League with the best team, then on the bench have three, four, five good substitutions ... The squad doesn't allow to lose four players in this moment.
"The important teams that are going to fight to win, the title contenders, you see them when you play every three days because you need a deep squad and strong squad with quality. We have only just started our process.
"If we play one game every six or seven days, I think we can fight for something important.
"To play every three days, I think we have to be patient and not be disappointed too much."
Newcastle laid down a marker in the battle for a place in next season's Champions League as Eddie Howe's men edged ahead of Chelsea and Manchester United into fourth place - two points behind Spurs.
Backed by the Saudi sovereign wealth fund, Howe will be given further resources to strengthen in the January window, posing a major threat to the traditional powers for a place in the top four.
But the Newcastle boss claimed putting his side's rise down the club's new-found wealth is unfair on the efforts of his players, many of whom were signed before the Saudi takeover.
"The problem is that [the money] takes away the credit from the players," said Howe.
"We're enjoying the moment but we won't be getting ahead of ourselves."