Mikel Arteta has insisted mounting injury problems will not distract Arsenal from their attempts to win the Carabao Cup after he confirmed Ethan Nwaneri is the latest forward to be sidelined.

The 17-year-old was substituted at half-time of Saturday’s 1-1 draw at Brighton on Saturday after he had given Arsenal the lead, with Arteta revealing that Nwaneri is expected to be out for “a few weeks”.

Related: Premier League: 10 talking points from the weekend’s action

That leaves the Arsenal manager short of options in attack for the first leg of their Carabao Cup semi-final against Newcastle on Tuesday given the prolonged absence of Bukayo Saka. Arteta could not guarantee that Kai Havertz would return after missing the last two games owing to illness, but he was adamant that his squad can cope as they aim to win only a second major trophy since he took charge five years ago.

“It’s the icing on the cake,” Arteta said when asked how important it was to end the season with silverware. “We work every single day to achieve that to bring joy to our people and there is not a single moment that stands out more than when you have that cup, and you are offering that cup to the supporters, and you are sharing it with the people you work with every day. They are memories that stick in your mind and hopefully we can create many more.

“You see a lot of clubs and how they prepare and how they decide lineups and there is a lot of talk about the cups and how it is right now. It’s very different because we know to win any trophy in this environment, especially in this country, is extremely difficult.”

Asked when the Carabao Cup had become a priority for Arsenal, Arteta said: “From the beginning. It’s something that we discussed and were very clear: we want to win every competition. We are here and we have a squad and we have levels that require that we approach every game in that way. We started game by game, now we are in the semi-finals and we want to make it happen.”

Gabriel Martinelli is expected to return to the starting lineup against Newcastle, while Martin Ødegaard has also been battling illness. Arteta rejected suggestions that his team had been too negative after taking the lead against Brighton before they were pegged back by João Pedro’s controversial penalty.

“Sometimes you are not good enough in certain areas and that doesn’t allow you to do that,” he said. “It’s certainly not the intention but you have to give credit to the opposition as well.”