Existe uma maneira de aninhar rotas no React Router v4?

Isso funciona:

  <Router basename='/app'>
    <main>
      <Route path='/' component={AppBar} />
      <Route path='/customers' component={Customers} />
    </main>
  </Router>

Isto não:

  <Router basename='/app'>
    <Route path='/' component={AppBar}>
      <Route path='/customers' component={Customers} />
    </Route>
  </Router>

Componente de clientes:

import React, { Component, PropTypes } from 'react'
import styled from 'styled-components'

export default class Customers extends Component {
  render () {
    return (
      <Container>
        <h1>Customers</h1>
      </Container>
    )
  }
}

const Container = styled.section`
  height: 100%;
  padding: 15px;
  overflow: auto;
`