Cristiano Ronaldo

Cristiano Ronaldo is the focus on the Portugal team, despite his injury which could limit his effectiveness Sunday against the U.S. (Jose Sena Goulao / EPA / June 21, 2014)

Portugal always relies on Cristiano Ronaldo, and it will have to do more than ever in Sunday's World Cup game against the U.S.

The Portuguese, diminished by injury and suspension, need not only a positive result but multiple goals to help close their goal differential of minus-four in case the tiebreaker kicks in to determine which Group G teams advance to the round of 16.

So they will lean extra heavily on the two-time FIFA world player of the year who is coping with so much knee tendinitis and thigh soreness that his personal physician made a surprising disclosure to a Portuguese newspaper. He advised Ronaldo to shut it down.

Teammates say Ronaldo has looked sufficiently fit in practice, and he evidently did not entertain the notion of following his doctor's advice. Whether the decision is self-serving -- Ronaldo has an estimated $28 million in annual endorsements to protect -- or devotion to the team, it does not matter.

He craves the spotlight, and it will not get much brighter than now.

Ronaldo is estimated to run about six miles per game, less than many forwards but still exhausting, particularly when impeded by nagging ailments. As much danger as he generates while in motion, his effectiveness carries over to set pieces. He is uncanny on free kicks, so a less mobile Ronaldo does not mean a useless Ronaldo.

Still, Portugal is banking on him to score goals and setting them up too.

It is usually over-simplistic to say that containing one player out of 11 guarantees victory. For the U.S., fencing in the most explosive scorer besides Argentina's Lionel Messi should bring the outcome it desires.