Madrid (AFP) - Barcelona and Real Madrid face difficult trips in their first away games of the La Liga season on Sunday when they travel to Villarreal and Real Sociedad respectively.
Croatian international Ivan Rakitic also made his competitive debut at the Camp Nou and has already taken to playing alongside Messi.
"I don't need to talk about him, we already know he is the best in the world," he said on Thursday.
"I thank God that I am able to play in the same team as him.
"I am enjoying the chance to play with the best players in the world. I want to make the most of this opportunity and the good performances motivate me even more.
"The most important thing is that we get better. There have been a lot of changes in all positions, but you will see a continuos improvement."
Despite his star turn last weekend, Munir is likely to drop to the bench as Brazilian star Neymar has returned to training following a sprained ankle which ruled him out against Elche.
Gerard Pique also returns from suspension and is expected to replace the banned Mascherano.
Madrid were less convincing in seeing off newly promoted Cordoba 2-0 on Monday and have also seen two key members of the side that won the Champions League last season.
Angel di Maria has completed his British transfer record transfer to Manchester United, whilst Xabi Alonso is on the verge of a shock move to Bayern Munich.
However, World and European Player of the Year Cristiano Ronaldo believes summer signings James Rodriguez and Toni Kroos can fill the void left by Di Maria and Alonso.
"If this Real Madrid is better or worse than last year we will see at the end of the season," the Portuguese captain told Madrid sports daily Marca.
"You can buy the 40 best players in the world and it doesn't necessarily make you a great team.
"I am not saying that the players Real Madrid have bought aren't top players. They are great players and are going to help Real Madrid, but the overall result comes at the end of the season.
"We will see if we win more or less than last season, but I am convinced that things will go well for them individually and for us at a collective level."
Madrid boss Carlo Ancelotti blamed tiredness for his side's below par display against Cordoba after two draining Spanish Super Cup ties against Atletico Madrid, but Real will have the advantage of a free midweek before travelling to San Sebastian to face Sociedad.
The hosts, meanwhile, will have just returned from an arduous journey to Russia as they faced FK Krasnodar in the Europa League on Thursday.
Champions Atletico also paid for their exertions in the Super Cup as they were held in the opening game of their La Liga defence in a drab 0-0 draw at local rivals Rayo Vallecano on Monday.
However, they will be heavy favourites to secure their first win of the campaign when they host tiny Basque club Eibar, who beat Sociedad last weekend to celebrate their first ever match in the Spanish top flight in style.
Fixtures (all times GMT)
Cordoba v Celta Vigo (1600), Athletic Bilbao v Levante (1600), Atletico Madrid v Eibar (1900), Espanyol v Sevilla (2100)
Villarreal v Barcelona (1600), Deportivo la Coruna v Rayo Vallecano (1800), Real Sociedad v Real Madrid (1800), Elche v Granada (2000)