Arsenal
Arsenal need to improve their attack, and make sure to score as many goals as the opportunities as they create. If Arsenal gets a good striker in the transfer chance and get reinforcements in some other positions in the team, their chances of doing very well in the champions league round of 16 more than they did in the group stages will be higher.
Arsenal have just suffered a defeat in the EPL, unfortunately the defeat occurred at the Emirates Stadium, which is their home ground. Mistakes that occur in the EPL must be avoided in the UCL, this is a knockout competition, only the team that consistently wins will survive. The transfer market could possibly be used to exchange players or bring in new players by buying them permanently, the defeat to West Ham showed that their front line was very dull. To be able to survive and win the UCL trophy, Arsenal must be able to maintain the team's performance so that it continues to be consistent in all areas, last season Manchester City succeeded in winning its first UCL trophy, Arsenal must try it with impressive play as shown by Manchester City last season.