Arsenal could again be without both their first-choice center-backs when they travel to take on Newcastle United on Saturday. Laurent Koscielny, with a back injury, and Per Mertesacker, through illness, were both ruled out of Monday’s goalless draw with Liverpool, and Arsene Wenger remains unsure whether the duo will be able to return at St James’ Park.

“Mertesacker is still sick and we will know more about Koscielny today,” he said at his pre-match press conference on Thursday. “He might have a test on his back today and I will certainly know more tomorrow morning. The less likely to be fit is Mertesacker.”

The pair were sorely missed on Monday night as Gabriel and particularly Calum Chambers endured a tough time against Liverpool to leave Arsenal with just four points from their opening three Premier League games. With Manchester City already five points in front, Wenger will be well aware that his team needs to be firing on all cylinders, making the potential absence of Koscielny and Mertesacker a particular blow.

“I would like them to be available but that’s part of the season, you can’t complain about that,” he added.

As well as long-term injury victim Tomas Rosicky, Arsenal will once again definitely be without Danny Welbeck and Jack Wilshere. Welbeck’s wait for a return will now go on until Arsenal’s first game following the international break against Stoke City on Sept. 12. The England forward has been missing with a knee injury since the tail-end of last season. Wilshere, meanwhile, picked up the latest in a long line of ankle injuries on the eve of this season when suffering a hairline fracture to his right ankle.

“Danny Welbeck  is progressing well,” Wenger said. “He should be available, if all goes well, after the international break. Jack Wilshere is just behind Welbeck, maybe one week after the international break he will certainly come back into full training.”

Wenger has admitted his disappointment at Arsenal’s poor start to the season, particularly having stressed the importance of beginning the campaign well. Last season, the Gunners won just two of their opening eight Premier League matches, leaving them too much to do in order to mount a real title challenge, despite a strong second half of the campaign. But the Arsenal boss stressed that he feels more is to come from his squad when they, and Alexis Sánchez in particular, get up to full speed.

“I think we are ready to play 90 minutes but its normal as well that after two or three games you’re not completely at 100 percent, because that’s coming slowly,” he explained. “We have started late and as well some players have come in, like Sánchez on the 1st of August. He’s not completely there.”