Stanford grad Tony Azevedo was one of three players to score a pair of goals, though the USA men's national water polo team fell, 11-10, to Greece in group play at the FINA World Championship in Kazan, Russia on Wednesday.
Team USA (16-17-1 overall) returns to action against Italy on Friday.
Greece scored the final three goals to erase a 10-8 deficit.
Team USA got off to a great start as Mann scored out of two meters just moments into the match for a 1-0 lead. Greece responded quickly with a goal on their next possession and the game was even at 1-1 with less than a minute gone by.
The teams would continue to trade goals for the rest of the period as Samuels fought off the Greek goalkeeper for a score only to see Ioannis Fountoulis answer to even the match at 2-2.
Luca Cupido connected for a score with less than four minutes to play to retake the lead at 3-2. That was short lived as Fountoulis connected again on the counter attack for a 3-3 match after one period.
Samuels was on the money again to start the second period, scoring in the opening minute for a 4-3 lead. Fountoulis responded yet again only to have Mann and Azevedo answer as Team USA took a 6-4 lead into halftime.
In the third period, Greece got on the comeback trail with their center game as Konstantinos Mourikis scored two of the first three goals of the period.
Stanford grad Alex Bowen and Stanford senior Bret Bonanni delivered goals to keep the USA lead at two goals at 8-6 with 4:06 to play in the period.
After Greece scored to draw within one with a little over a minute to play, Azevedo came back with a goal outside five meters for a 9-7 lead with 46 seconds to go.
Greece had the last word in the period with Fountoulis connecting for his game high fourth goal of the match, leaving Team USA ahead just 9-8 going to the fourth.
The final period stayed quiet until the 4:05 mark, when Alex Roelse connected for a score and a 10-8 lead. Greece then proceeded to go on its run.
Emmanouil Mylonakis scored two straight to even the match at 10-10 with 1:44 to play. Then, with 31 seconds left, Evangelos Delakas delivered in close for the game winning score.
Team USA went 5-of-10 on power plays and did not attempt a penalty shot while Greece was 2-of-5 on power plays and did not attempt a penalty shot.