Have Arsenal's challengers done enough?

[BBC]Arsenal have started the new Premier League season with two wins as the transfer window closes, looking in ominous shape to retain the crown they won for the first time in 22 years last season.Have their main rivals done enough to prevent Mikel Arteta's side winning a second successive title?And what are the other big issues as the Premier League's transfer business was concluded until January?Liverpool's main task this summer after appointing Andoni Iraola to replace sacked Arne Slot, was