European football returns this week as the Champions League and Europa League 2019/20 campaigns begin.
Man City are looking to improve on their quarter-final defeat last term in the Champions League and are favourites to take home the trophy next year.
Manchester United are facing a season in the Europa League after their sixth place finish last term although they are also favourites to lift the trophy at the end of the season.
Both sides will be facing a number of rule changes for the 2019/20 European campaign agreed by the International Football Association Board (IFAB).
Here's what you need to know.
Champions League and Europa League rule changes
Substitutions
The first rule change means teams are now able to name squads of 23 and pick from 12 substitutions.
Free-kicks
We've already seen this change in the Premier League. It sees attacking players stopped from impacting the defensive free-kick wall. Attackers will have to be at least one metre away from the wall.
Goal-kicks
Goal-kicks and free-kicks inside the box don't have to leave the penalty area. It must be mentioned that the opposition is still not allowed to be inside the penalty area.
Drop balls
Drop balls will be allowed to be given straight to the keeper. Players will have to be four metres away and the ball will be dropped for the team which last touched it.
Penalties
Penalty changes will see keepers forced to have one foot on the goal-line when a spot-kick is taken. They will also not be able to touch the goalpost.
Departing the field
A player who has been substituted must leave the pitch at the nearest point on the field, as already seen in the Premier League.
Coin toss
Whoever wins the toss will now have the choice to kick-off or pick which end they will play from.
Manager cards
Coaches and managers can be handed yellow and red cards for different levels of misconduct.
Handballs
If an attacking player uses their hand or arm to either score or create a goal then it will be wiped out and labelled a handball offence.
