Mbappe netted twice when France beat Senegal 3-1 and two more in Monday's 3-0 win over Iraq to sit two goals behind Messi on the all-time list.
After a difficult season, the 27-year-old Real Madrid forward is back playing with a smile on his face and a real spring in his step.
Spain struggled without Yamal in the scoreless draw against Cape Verde, but on Sunday the 18-year-old started his first game in two months and the sense of anticipation was palpable inside Atlanta Stadium.
The crowd were on their feet as Yamal netted the opening goal to inspire Spain in a 4-0 win over Saudi Arabia.
Spain's job was done by halftime, allowing them to replace Yamal, who played with the abandon of someone who does not feel the weight of a nation's expectations on his young shoulders.