Mohammad Isam is ESPNcricinfo's Bangladesh correspondent. @isam84
Shakib Al Hasan's preparations for the World Cup kicked into high gear at this year's IPL. Left out by Sunrisers Hyderabad for four weeks, Shakib used the time to get into shape through a strict fitness regime under trainer Jade Roberts. At one stage he flew in Mohammad Salahuddin, his mentor since childhood, to India to work on his batting and bowling.
Shakib even changed his food habits and lost around six kilos. He looks slimmer, almost like the youngster he was during the 2007 World Cup. His work during the downtime which coincided with the run-up to the World Cup worked a treat. He played only three matches for Sunrisers before heading home for the World Cup camp in Dhaka. After creating a rumpus for not appearing in the team photo, Shakib did well in the Ireland tri-series, only to miss the final due to back spasm.
After Bangladesh beat West Indies in their first game in Dublin, Shakib spoke about the extensive fitness work he had been putting in with his eyes on the World Cup.
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"With the World Cup coming up, like every other player I too have a goal," he said in Ireland. "I can tell you that I have taken the best preparation for this tournament, something that I had not done for the past eight or nine years. I will keep my end of the bargain, while the rest is up to Allah and my effort.
"I feel a lot fitter than before, and as a result I feel more confident. It is important to hold on to this fitness, because it is not always that you have this mentality. The body doesn't respond in the same way all the time. I got a "kick" from somewhere, let's not reveal it. It is not a big deal but it certainly woke me up."
Cut to the World Cup itself and Shakib begins the campaign in the best way possible with a composed 75 off 84 balls and 1 for 50 from his ten overs. It was his first Player-of-the-Match award in the World Cup, having now struck a fifty in each of the four editions he has been a part of. This innings - which formed part of a 142-run stand with Mushfiqur Rahim - ensured there was no slip after a terrific start provided by Soumya Sarkar's bristling response to South Africa's attempts to use the short ball.
His bowling was also effective against a South Africa side that looked to be too conservative against his left-arm spin. The wicket he claimed, defeating a well-set Aiden Markram in his fifth over, was his 250th in ODIs. His initial spell of seven overs went for just 25 runs and was key in leaving South Africa significantly behind the required rate.
"From a personal point of view, it was a really good day," he said. "I could contribute to the team, and there were some personal achievements. It was an important partnership with Mushfiq bhai after we got a good start from the openers.
WATCH on Hotstar - Shakib's key innings (Available to viewers in India only)
"I think it was a special day for Bangladesh cricket, to start so well against tough opponents in the World Cup. We had the belief but we had to portray it in our performance. Everyone had been confident, which helped us to execute our plan."
Shakib, who will play his 200th ODI against New Zealand on June 5, said the 21-run win will have put opposition on notice when they face Bangladesh although cautioned against getting carried away by one victory.
"We still have eight matches to go, so a lot of difficulties await us. Other teams will now be careful against us. It is good because they may be a tensed facing us. But at the other hand, they would also be quite focused and we have to do well against them. We have to prepare better, and execute our plans better.
Shakib added that Bangladesh, who reached the quarter-finals of the 2015 World Cup and the semi-finals of the 2017 Champions Trophy, still have a lot to prove but the tag that they are a dangerous side is something he wants other teams to focus on.
"We have always tried to say it but others don't really have time for us. I think we have a lot to prove. We have started well. I think that we are in a good place, mentally. I think if we can continue in this manner we can go a long way in the tournament."
But it is Shakib's drive to do well, despite having been around for more than 13 years, and having earned plaudits for being arguably the best allrounder in the world, that stands out. Him performing at the top of his ability is nothing new but he has sometimes been associated with the sort of player who doesn't need a lot of day-to-day training to perform well. However, ahead of this World Cup his extra effort shows how much doing well at the biggest stage matters to him.