A Lottery Solidity Smart Contract

Lottery.sol

pragma solidity ^0.4.21;

contract Lottery {
  address public manager;
  address[] public players;

  constructor() public {
    manager = msg.sender;
  }

  function enter() public payable {
    require(msg.value > .01 ether);

    players.push(msg.sender);
  }

  function random() private view returns (uint) {
    return uint(keccak256(abi.encodePacked(block.difficulty, now, players)));
  }

  function pickWinner() public restricted {
    uint index = random() % players.length;

    players[index].transfer(address(this).balance);

    players = new address[](0);
  }

  function getPlayers() public view returns (address[]) {
    return players;
  }

  modifier restricted() {
    require(msg.sender == manager);
    _;
  }
}

I think there is a backdoor, the 'manager' (who deploy the contract) can figure out the winnning number by invoking the pickWinner function, the 'manager' can then bet on the winning number.

Note: The called function should be payable if you send value and the value you send should be less than your current balance.
Debug the transaction to get more information?