Arteta conceded on Friday that he was initially worried that the club would lose captain Pierre-Emerick Aubameyang in the transfer window.
The new Premier League season will begin on Saturday.
Sanchez has said he was ready to end his ill-fated spell at former club Manchester United after only one training session with the Premier League side.
The Egyptian returned to the Gunners after spending a season-long loan in Turkey playing for Besiktas.
The Reds aim to open the new season with a win and achieve the FA Community Shield award for the first time since 2006.
Arsenal are confident striker Pierre-Emerick Aubameyang will sign a new contract which would tie him to the club for a “long time”, manager Mikel Arteta said.
He has been an assistant and first team coach in Sweden since 2010, his last job being with former club Helsingborgs.
Liverpool will begin defending their Premier League title on Sept. 12 at Anfield.
Arsenal have signed Brazil winger Willian on a three-year deal, the Premier League club said on Friday.
British media has reported that Willian is on the verge of joining Chelsea’s London rivals Arsenal.
Coach Dick Advocaat is trying to persuade the 37-year-old to join his staff.
The two players picked up injuries during Chelsea's 2_1 loss to Arsenal in FA Cup final and they were forced to leave the pitch.
Arsenal won the title for for a record 14th time and secured their spot at Europa League next season.
Arsenal are desperate to win the title and secure a spot at Europa League to save their season.
Martinez says he has a point to prove in the FA Cup final against Chelsea on Saturday as he looks to shake off the tag of back-up goalkeeper.
Arsenal were outclassed 4-1 by Chelsea in the Europa League final in Baku last year.
Arsenal defender Shkodran Mustafi will miss the start of next season after having surgery on his hamstring, the Premier League club said on Tuesday.
The Egyptian winger has been sensational for his club during the last two weeks.
The Egyptian midfielder blasted home in the 27th minute and it proved enough for Villa to move above Watford on goal difference after they were thrashed by Manchester City earlier.
Mikel Arteta offered further evidence that Arsenal may have found the manager to lead them back to glory as he masterminded a 2-0 win over his former club Manchester City in the FA Cup semi-final at Wembley on Saturday.