Afghanistan captain Rashid Khan said Thursday his team must keep up their momentum after their ODI series win in Bangladesh, as they prepare for a two-match Twenty20 series and the World Cup.

The opening match of the Twenty20 series against Bangladesh will be played in Sylhet on Friday, with Afghanistan starting as favourites having won six of their previous nine matches.

"As a team, the main focus is to get better each day," Khan told reporters, adding that they were expecting different conditions on a wicket that should favour spin bowling.

Khan was rested for the third ODI after Afghanistan won the first two matches and takes the helm of the T20 side from Hashmatullah Shahidi.

"It's going to be a great contest and great game to watch."

Khan said the team wanted to put on an improved showing in the T20s, adding it would be good training for the tough matches ahead.

"It's preparation for us as a team for the World Cup... that will be our main focus," he said.

Afghanistan beat Bangladesh 2-1, their first ODI series win in Bangladesh in three attempts.

"We just need to keep that momentum for the Asia Cup and World Cup and try our best," he said.

Bangladesh skipper Shakib Al Hasan said he was relishing the challenge of facing Afghanistan in T20s, a format that suits the visitors better.

"We played well in the last two home series," Shakib said. "This is a new challenge for us. Afghanistan are definitely a very good team."

Bangladesh defeated world champions England in T20s 3-0 at home in March, before chalking up a 2-1 win over Ireland.

The second match of the series will also be held in Sylhet on Sunday.