The 26-year-old set Arsenal back an initial fee of £46.5 million ($60.3 million, 51.5 million euros) and is expected to lead the line, flanked by Sanchez and Ozil.
Sanchez's Arsenal future has been subject of intense speculation throughout the off-season with Bayern Munich and Paris Saint-Germain backing out of a chase for the Chilean, who reportedly still interests Manchester City.
But with Alexis Sanchez injured, Laurent Koscielny suspended and doubts surrounding Mesut Ozil, Aaron Ramsey and Per Mertesacker, there is every reason for Arsenal fans to feel a bit anxious.
However, Arsene Wenger has been adamant that Sanchez is not going anywhere and it is likely that the new contract can see him continue at the Emirates for more than one more season.
With Sanchez having less than 12 months on his contract and no new deal signed, the skeptics out there (definitely not myself included...) could suggest that this injury is rather timely given that Sanchez may not return to action before the summer transfer window shuts on August 31.
Alexis Sanchez returned to Arsenal training on Friday as manager Arsene Wenger maintains his stance that the forward will not be sold.
Wenger added: "I'm convinced in 10 or 15 years it will not necessarily be a football specialist who is a manager of a club".
Who are we to believe? Why hasn't he just said I'm staying for one more season? If they succeed in bringing him in, Wenger will have a squad depth and quality that could compete for the Premier League title this year.