A strong opening partnership is a must when a team wants to chase the target. Just think of the match between Sri Lanka and Afghanistan. 243 runs is a reachable target, but with pressure, it isn't an easy score. Look at the performance of Afghanistan. They kept losing wickets from the beginning. With the win, Sri Lanka has almost qualified for the semifinals from Group B. In Group A, India and Pakistan might get qualified. Right now, the UAE, with a win, stands in the first position. India has lost to Pakistan and stands in the third position, and Japan stands last.
I agree with your point that if opening of match is strong and winning chance increase significantly. It also motivates next batters and strong spirit arises just like Sri lanka Under 19s batting Inning. Their first batter Dulnith Sigera was not succeeded to express their strong inning but next two batters Sharujan Shanmuganathan and Pulindu Perera build strong batting partnership with long inning and both batters managed 102 and 53 scores respectively. Sri Lanka Under 19s squad managed to collect 243 scores as a defend by playing 50 overs and this scores made great determination to bowlers. Their bowlers turned out this match to one sided by picking crucial wickets of Afghanistan Under 19s squad in early stage. Praveen Maneesha cleared out 3 crucial wickets of Afghanistan Under 19s squad and put burden to their batters and all wickets were lost at 112 scores and simply they achieved victory.