Ooh, Trinity Rodman goes down in the area after a clumsy tackle from Thi Thu Tran.

Bouchra Karboubi says no penalty, but VAR are checking...

Neil Johnston
BBC Sport at Eden Park

What a noise! Vietnam launch a first serious attack and the whole stadium erupts. More noise for that than Sophia Smith's goal.

Vietnam have a rare foray into the American half, and striker Huynh Nhu performs a lovely turn to leave her marker behind. The crowd liked that.

The attack comes to nothing, but no doubt who the neutrals are backing at Eden Park.

Ertz actually did herself more of a mischief as she mistimed her header. She gets some treatment and will be fine.

In the meantime the American players get some water and stern words from manager Vlatko Andonovski.

They haven't rolled over Vietnam as we perhaps expected after the early goal.

Now Smith wins a corner off Diem My.

It's played deep, Julie Ertz meets it with a header and gets clattered in the process.

Kim Tranh can't gather in the Vietnam goal, however her defence helps out.

Sophia Smith gets a half-chance, but can only volley well over the top.

It should have been a corner as replays show it took a deflection off Vietnam defender Diem My, but a goal kick was given.

The USA keep pouring forwards.

Emily Fox pings in a deep cross from right back which Kim Tranh can only punch out to Lindsay Morgan, who sends her first time shot just wide.

Vietnam hang on for now.

Morgan is played in again, but this time is slightly offside.

It was a good piece of goalkeeping too by Kim Tranh, who smothered at Morgan's feet.

So close to number two!

Savannah Demelo - who has been outstanding on debut so far - plays a brilliant reverse through ball to Alex Morgan, who flashes a shot across goal.

Nearly her 10th goal in World Cups.

The first corner of the game comes as a Sophia Smith shot is deflected behind.

The official has a quick word with Alex Morgan for bumping into keeper Kim Tranh before the set piece is taken.

The deep corner is cleared and Vietnam deal with any follow ups.

Vietnam's last game before this one was a behind closed doors friendly against Spain. They lost 9-0.

They must fight to avoid a repeat here. As perhaps expected, this game is now looking like an attack v defence drill.

Savannah Demelo is very keen on that debut strike.

Trinity Rodman does well to cut back a low cross from the right byline, and Demelo again shoots first time. This time it is blocked, then cleared from a few yards out.

Neil Johnston
BBC Sport at Eden Park

The defending world champions are up and running. Great camaraderie in this USA squad, with all the substitutes out of their seats to applaud Sophia Smith's goal.

The champions are hunting now.

Savannah Demelo almost grabs a debut goal, however her shot on the turn from 12 yards out is well saved by Kim Tranh.

Sophia Smith was named the NWSL's most valuable player last year.

We will be seeing and hearing a lot more about her over the next month, and in the coming years.

It was after 12 minutes that the USA scored the first of their 13 goals against Thailand. Vietnam have got past that point unscathed.

Vietnam have a long way to go, but so far have looked strong and disciplined.

Moroccan referee Bouchra Karboubi initially gives a corner to USA, however is informed the ball came last off Lindsay Horan so changes her decision to goal kick.

Neil Johnston
BBC Sport at Eden Park

Four attempts by the defending world champions already - one blocked, one over the bar, one wide, one saved although the flag was up.

By the way, Eden Park is not full for this. It's lively, it's noisy but there are empty seats. If I was to take a wild guess, I'd say there are around 30,000-35,000 inside.

Worth noting that for all the World Cup winning nous in this American side, this is the most inexperienced USA XI at a World Cup since 1995 in terms of caps.

The new blood includes Rodman, talented striker Sophia Smith, and midfield Savannah Demelo who is making her international debut today.