Arsenal’s win over Sheffield United pleased boss Mikel Arteta but his joy was tempered by injury concerns over Bukayo Saka and Gabriel Martinelli.

Both players had to be withdrawn during the 3-0 victory at Bramall Lane, where Arteta was already without Pierre-Emerick Aubameyang, Martin Odegaard and Emile Smith Rowe.

Saka went to ground holding his thigh following a collision with Blades striker Rhian Brewster and made the sensible decision to come off the field. Martinelli twisted his ankle and looked set to come off moments before scoring the Gunners’ second goal.

Both Aubameyang (illness) and Smith Rowe (ankle) face a race against time to be fit for the Europa League showdown with Slavia Prague on Thursday night.

Arteta will be desperate to have key players back for the trip to Czech Republic, for a match that could define Arsenal’s season.

The Gunners boss said: ‘It was a strong performance, efficient and intelligent with the ball and the right attitude. I am really happy, but the injuries are a worry.

‘[Saka] had some discomfort in his thigh. I don’t know what it is. The last thing we need is another issue because we have enough of that and are missing some big players at the moment.

‘I don’t know the extent but we will see how it develops in the coming days. Martinelli twisted an ankle and it was sore, but he’s a tough boy.’

Asked if Aubameyang will be fit to face Sparta on Thursday, when Arsenal must score if they are to stay in the Europa League after drawing 1-1 in the home leg, Arteta said: ‘I hope so.

‘He was unwell yesterday and could not train. Hopefully in the next day or two he will be feeling better and will be available.

‘As for Emile and Martin, we don’t know yet. Kieran Tierney is out – probably for the season.’

Arsenal’s opening goal at Bramall Lane was one of real beauty. Some lovely one-touch football around the edge of the penalty area involved Saka, Thomas Partey and Dani Ceballos, whose deft backheel flick eventually put Lacazette through on goal to slide the ball beneath Aaron Ramsdale.

It was not quite of the level of the Gunners’ much-celebrated team goal against Norwich in 2013, scored by Jack Wilshere, but it had many of its hallmarks.

Arteta, who was in the Arsenal team on that occasion, said: ‘It was a typical Arsenal goal, really high quality. It was a quality finish and movement from Laca as well. He is playing really well and scoring goals.

‘He has a high level of confidence and hopefully it will keep right up until the end of the season because if it continues it means the team is doing well and winning matches.’

Lacazette’s strikes either side of Martinelli’s goal inflicted a 25th Premier League loss of the season on the Blades and they remain rooted to the bottom of the Premier League table.

A third straight defeat for interim boss Paul Heckingbottom – a second in the league – leaves the South Yorkshire club 18 points from safety with seven games to go.

‘It’s an unforgiving league,’ said Heckingbottom. ‘Just as I thought we were having our strongest moments in the game, we conceded a second goal which took the wind out of our sails.

‘We have to keep going. The season we’ve had as a club has taken its toll but you have to look forward. The moment you want to have a breather and not give 100% then you are no good to the team.

‘We want to catch [19th-placed] West Brom – it’s some pride and meaning for the club, and also a financial reward which we are obviously keen on.

‘We need to make sure we get the most out of what is left to prepare for next season.’